European Journal of Inorganic Chemistry

Current research reports and chronological list of recent articles.


The scientific European Journal of Inorganic Chemistry - EurJIC - is the fastest growing journal in inorganic chemistry. It publishes Full Papers, Short Communications, and Microreviews from the entire spectrum of inorganic, organometallic, bioinorganic, and solid-state chemistry.

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Additional research articles in the field of inorganic chemistry, see Current Chemistry Research Articles. Magazines with similar content:

 - Dalton Transactions,

 - Inorganica Chimica Acta,

 - Inorganic Chemistry,

 - Inorganic Chemistry Communications,

 - European Journal of Inorganic Chemistry,

 - Russian Journal of Inorganic Chemistry.



European Journal of Inorganic Chemistry - Abstracts



Apatite-like complex oxides in the Ca-Cr-Cu-O system: synthesis, crystal structure, XPS and magnetic study

Calcium chromates Ca5(CrO4)3Cux(OH)1-x with apatite structure and different content of copper and OH¯ groups have been synthesized by solid phase reactions under usual conditions in air. The composition, structure, degree of oxidation of elements and the properties of the produced chromates have been characterized by X-ray diffraction, photoelectron spectroscopy XPS, thermal analysis (DTA and TGA) and magnetochemistry methods. It was concluded that the reason of apatite stabilization is the introduction of Cu+ and Cu2+ cations into the hexagonal sites O(4) in the tunnels of the Ca5(CrO4)3OH apatite structure owing to substitution of OH- by the scheme OH¯ ¬(Cu+O)¯ or 2OH¯¬ (Cu2+O2)2-- giving rise to infinite chains along the с axis.
Datum: 26.09.2016


Zinc(II) Complexes of N,N-Di(2-picolyl)hydrazones

We report N,N-di(2-picolyl)hydrazone (DPH) ligands that are capable of binding metal ions in two isomeric forms depending on the nature of the hydrazone substituent. When the hydrazone substituent is not coordinating, the metal ion prefers the N,N-di(2-picolyl)amino (DPA) site, which is a known tridentate ligand that anchors on the sp3-hybridized amino nitrogen. When the hydrazone substituent is coordinating, the metal ion instead anchors on the sp2-hybridized imino nitrogen to afford a different structural isomer. Zinc(II) is used as a representative transition metal ion for characterizing the coordination chemistry of DPH in both solution and solid states.
Datum: 23.09.2016


Binary Polyazides Of Zinc

Herein, we report on the synthesis, isolation and comprehensive characterization (M.p., ATR-IR/Raman, elemental analysis, 14N NMR) of tetraazido zincate anions [Zn(N3)4]2− in a series of [Ph4P]+ and [PNP]+ (PNP = bis(triphenylphosphine)iminium) salts. The phase polymorphism in [Ph4P]2[Zn(N3)4] was investigated by temperature dependent Raman, powder and single crystal X-ray diffraction experiments, which indicate the occurrence of five room-temperature stable, and one common high-temperature phase, besides two polymorphs of the acetonitrile solvate [Ph4P]2[Zn(N3)4] · MeCN. Moreover, the synthesis of zinc azide solvates Zn(N3)2 · n solvent (solvent = DMSO, n = 1, 3/2, 3; MeCN, n = 2/3) is presented for the first time. Single crystal X-ray structures of all new compounds were determined. For a better understanding of structure and bonding in E(N3)2, [E(N3)3]− and [E(N3)4]2− (E = Zn, Cd, Hg), theoretical calculations at the M06-2X/aug-cc-pVDZ level were carried out.
Datum: 23.09.2016


Improved Syntheses of 1,2-Disubstituted Ferrocenes

1,2-Disubstituted ferrocenes, in particular 1,2-dihaloferrocenes, are important starting materials. Herein, we describe significantly improved high-yielding syntheses of 1,2-disubstituted ferrocenes such as 1,2-dibromo- and 1,2-diiodoferrocene as well as 1-bromo-2-iodoferrocene, and 1-bromo-2-fluoroferrocene. DFT calculations show that 1,2-dihaloferrocenes do not differ much in their highest occupied molecular orbital (HOMO) energies; however, their lowest unoccupied molecular orbital (LUMO) energies – and thus the HOMO/LUMO gaps – correlate with the sum of the halogen electronegativities. In addition, a synthesis of the rather sensitive 2-aminoferrocenecarboxylic acid, the ferrocene analogue of anthranilic acid, is presented, which starts from ferrocene-1,2-dicarboxylic acid. However, 2-aminoferrocenecarboxylic acid rapidly decomposed and thus could not be properly characterized. Ferrocene-1,2-dicarboxylic anhydride serves as the starting material for preliminary photochemical decarbonylation/decarboxylation experiments resulting in 1,2-dideuterioferrocene when carried out in [D8]toluene.New or improved syntheses of useful 1,2-disubstituted ferrocenes are presented. These include 1,2-homo- and 1,2-heterodihaloferrocenes as well as ferrocene-1,2-dicarboxylic anhydride, which is a potential precursor for 1,2-dehydroferrocene and 2-aminoferrocenecarboxylic acid.
Datum: 23.09.2016


Synthesis, Structure and Solution Studies on Mixed Aryl/Alkyl Lithium Zincates

Novel homo- and heteroleptic lithium zincates have been prepared by cocomplexation reactions of Zn(CH2SiMe3)2 and PhLi in low-polarity hydrocarbon solvents. X-ray crystallographic studies of products obtained by reacting the organometallic reagents in benzene or toluene yield the novel solvent-free solid-state arrangement [Li4Zn3Ph5(CH2SiMe3)5]⋡ (1). Combining Zn(CH2SiMe3)2 and PhLi in hexane in the presence of the polydentate N-donors PMDETA (N,N,N′,N′′,N′′-pentamethyldiethylenetriamine) or TMEDA (N,N,N′,N′-tetramethylethylenediamine) reveals monomeric heteroleptic [(PMDETA)LiZn(CH2SiMe3)2Ph] (2) and homoleptic [(TMEDA)LiZn(CH2SiMe3)3] (3), the result of a disproportionation process, respectively. NMR spectroscopic studies suggest that 2 and 3 retain their discrete contacted ion-pair solid-state structures in benzene solution. Variable-temperature NMR spectroscopic studies of 2 in [D8]THF reveal a complex equilibrium also including [LiZn(CH2SiMe3)3], [LiZn(CH2SiMe3)Ph2] and [LiZnPh3], an equilibrium process analogous to that of 1 in THF. This study further highlights the complexity of these reactions, which at first would appear simple.Studies on the cocomplexation of PhLi and Zn(CH2SiMe3)2 have revealed a dramatic solvent effect and intricate solution behaviours as well as unique structural motifs in zincate chemistry.
Datum: 22.09.2016


Syntheses of Sterically Bulky Schiff-Base Magnesium Complexes and Their Application in the Hydrosilylation of Ketones

The sterically bulky Schiff-base ligand 1 (L1H) was treated with CH3MgI in toluene to give the unexpected homoleptic magnesium complex 2 (L1MgL1) in good yield. However, the reaction of sterically more bulky ligand 3 (L2H) with CH3MgI in diethyl ether yielded the desired heteroleptic magnesium iodide 4 [L2MgI(OEt2)], which was further reduced with sodium to produce the Mg–Na heterodimetallic complex 5. The crystal structures of all new magnesium complexes were determined by single-crystal X-ray diffraction. All new magnesium complexes have been investigated as catalysts for the hydrosilylation of ketones with (EtO)3SiH. The study showed that catalytic activity of the Mg–Na dimetallic complex 5 is superior to those of monometallic magnesium complexes 2 and 4 and is applicable to a series of subatrates.A series of sterically bulky Schiff-base magnesium complexes have been prepared, which could be used as catalysts for the hydrosilylation of ketones with (EtO)3SiH.
Datum: 22.09.2016


Family of novel titanium complexes with catechol ligands: structural investigation and catalytic application

From the reaction of Ti(OCH3)4 with catechols in methanol, four new titanium catecholate complexes have been obtained and structurally characterized: [Ti2(Cat)2(CatH)2(OCH3)2(CH3OH)2] (1) (Cat = C6H4O22-), [Ti2(4tBuCat)4(CH3OH)2] * 2 CH3OH(2 * 2 CH3OH) (4tBuCat=[4-tC4H9-C6H3O2]2-), [Ti(Cat)2(dmf)2] (3) (dmf = N,N-dimethylformamide), [Na(dme)Ti(Cat)3]2[Na(DME)CH3OH]2 (4) (dme = 1,2-dimethoxyethane). Complex 3 is the first example of the neutral mononuclear titanium catecholate, having more than 1 catechol molecule per titanium atom. Complexes 1 and 2 are neutral dimers, in the solid state, with a catechol/Ti ratio equals to 2, both having one of the catechol ligands bridging two titanium centers in a singly bridging chelate µ2-(O,О'O') mode. The other catechol molecule is either a terminal bidentate chelating ligand (2), or Ti monodentate ligand (1). Complex 4 is a heterometallic aryloxide complex with tetrameric[(Na(dme)Ti(Cat)3)2]2- (Ti2Na2) core, as an anionic moiety, and Na ions, solvated by methanol and dme ligands, [(Na(dme)(CH3OH))2]2+, as a cationic counterpart. Each Ti centre in 4 is octahedrally coordinated by three catechol ligands, demonstrating three distinct types of bridging modality. It was shown that 1-4 effectively catalyze selective homogeneous hydrogenation of acetylene to ethylene. Various kinetic dependencies were obtained and analyzed enabling to propose the reaction pathway for this catalytic reaction.
Datum: 21.09.2016


Synthesis of diferrocenyl hydrazone-enone receptor molecule: Electronic communication, metal binding and DFT study

Synthesis of four new diferrocenyl hydrazone-enone compounds have been carried out by two step reaction process involving 1,1'-diacetylferrocene, hydrazides and ferrocenyl carboxyaldehyde.Structural characterization of two compounds, 6 and 7 by single crystal X-ray diffraction study showed the presence of more stable eclipsed conformation with the two ferrocenyl moieties oriented in trans- geometry.Electrochemical and metal ion sensing properties for the diferrocenyl bifunctionalized compounds have been explored to understand their potential in electronic communication and as receptor molecule.Compounds, 1,1'-[(η5-C5H5)Fe(η5-C5H4)CH═CHC(O)(η5-C5H4)Fe{(η5-C5H4)C(CH3)═N-N(H)C(O)-R}] {R = C6H4-OH (6), C6H4N-p (7) }, showed selective interaction with Pb2+ metal cation and distinct binding interaction with BSA protein.The mode of metal-receptor interaction has been established by DFT studies.The redox properties for the diferrocenyl compounds with variable end groups revealed distinct electronic communication between the two electroactive groups.
Datum: 21.09.2016


Synthesis and investigation of solid and solution state structures of nickel(II) complexes with 1,3-dimethyl-5-(arylazo)-6-aminouracil

The nickel(II)-arylazo-6-aminouracil derivatives, [NiII(DMA3U)2], where HDMA3U (1-3) = 1,3-dimethyl-5-(arylazo)-6-aminouracil [arylazo- => phenylazo (1), p-Me-phenylazo (2), and p-Cl-phenylazo (3)] have been synthesized and isolated in crystalline forms. Single-crystal X-ray diffraction study of [Ni(1)2] reveals that in the complex the metal center has square planar environment. The intramolecular N-H/π and C-H/π interactions hold in the solid state as well as in poor-HBA (H-bonds acceptor) solvents, but are disrupted in good HBA solvents. Crystal structure analysis further shows that the -NH groups of the coordinated ligands are not available for H-bonding interactions in the solid state which have been corroborated by DFT calculations. Complexes exhibit multiple absorption bands in the UV-vis region and TDDFT study was performed to understand the origin of the ground state electronic absorptions. The complexes are found to be highly radiative in poor HBA solvents rather than in good HBA solvents. The complex-HBA solvents association constant (Kasso) values were determined UV-vis spectrophotometrically, which range from 1.18 - 2.51 M-1.
Datum: 21.09.2016


The Key Heterolysis Selectivity of Divalent Sulfur-Sulfur Bonds for the Unified Mechanistic Scheme in Thiosulfatolysis and Sulfitolysis of Pentathionate ion

The thiosulfatolysis and sulfitolysis of pentathionate were studied in the pH range of 4.50 to 8.0 and 4.0 to 5.0 at T = 25.0 ± 0.1 °C by high-performance liquid chromatography monitoring the time dependence and distribution of different sulfur species. The two systems were found to be first order with respect to both reactants. Different with tetrathionate, pentathionate and higher polythionates contain non-equivalent divalent sulfur atoms, causing the complexity of the mechanism. The selected heterolytic cleavages of sulfur-sulfur bonds were indicated to be the essential steps for time evolution and equilibrium distribution of divalent sulfur species. A proposed eight-step mechanistic model, incorporating the proton equilibrium of sulfite and the heterolytic cleavage of divalent sulfur-sulfur bonds of, hexathionate, were applied to evaluate both thiosulfatolysis and sulfitolysis of pentathionate ion, demonstrating that kinetics of both systems are modulated by this mechanistic network.
Datum: 21.09.2016


Heterobimetallic oxalate-bridged MIIReIV (M = Zn, Cu, Ni, Co and Mn) complexes incorporating bis(3,5-dimethylpyrazol-1-yl)-methane - Synthesis and magneto-structural studies

Five oxalato-bridged heterobimetallic compounds of general formula [ReCl4(ox)M(bdmpzm)2].2MeCN [ox = oxalate, bdmpzm = bis(3,5-dimethylpyrazol-1-yl)methane and M = Zn (1),Cu (2), Ni (3), Co (4) and Mn (5)] have been successfully synthesized in self-assembly reactions of the [ReCl4(ox)]2- metalloligand with the coordinatively unsaturated [M(bdmpzm)2]2+ complex generated in situ by the reaction of the suitable metal(II) salt with the bdmpzm ligand. 1-5 are isostructural compounds whose crystal structures consist of neutral heterodinuclear [ReCl4(ox)M(bdmpzm)2] units and free acetonitrile molecules. The magnetic properties of 1-5 were investigated in the temperature range 2.0-300 K. The nature and trend of the magnetic interactions in 2-4 is discussed in the light of the number and symmetry of the magnetic orbitals involved and compared with those reported in previous magneto-structural studies where the [ReCl4(ox)]2- was used as a metalloligand towards first-row transition metal ions.
Datum: 21.09.2016


Enhancing the cytotoxic activity of anticancer Pt(IV) complexes by introduction of lonidamine as an axial ligand

The synthesis and in vitro cytotoxicity of a series of Pt(IV) complexes with lonidamine as a ligand coordinated in axial position are described. The lonidamine was found to affect strongly the in vitro cytotoxic activity of these novel complexes, lowering the IC50 values down to the nanomolar range. Lipophilicity assessed in terms of log P showed no direct correlation with cytotoxicity.
Datum: 21.09.2016


Capturing Hydrophobic CF3I in Water into a M4L6 Cage

Synthetically important trifluoroiodomethane (CF3I) is trapped in water using a metallo-organic supramolecular anionic cage. At ambient condition, nearly 1:1 encapsulation of hydrophobic, gaseous substrate CF3I with cage was observed and its binding constant was calculated by relative comparison with benzene encapsulation
Datum: 21.09.2016


Dynamic Directing Effect and Symmetric Correlation in Three pH-Modulated 1,4-Diazabicyclo[2.2.2]octane/Iodoargentate Hybrids

Three iodoargentate hybrids, [(Hdabco)(H2dabco)][(Ag3I6)] (1), [(Hdabco)2(H2dabco)][Ag3I7] (2), and [(H2dabco·H2O)(AgI3)] (3) (dabco = 1,4-diazabicyclo[2.2.2]octane), have been synthesized by simply changing the pH of the reaction solution. The hybrids 1–3 are all constructed exclusively of corner-sharing AgI4 tetrahedra, but they clearly exhibit different structural features (typical halozeotype in 1 and 2, chiral chain in 3). Noteworthy, variation of the hydrogen-bonded aggregating forms of dabco at different pH, regular modulation of the inorganic moieties from the [3276] cage in 1 to the larger [32114] cage in 2 and a three-fold helical chain in 3, as well as their intrinsic symmetric correlation reveal unique dynamic structural directing effects and structural adaptability of the iodoargentate framework. Moreover, the three compounds display wide-band-gap semiconductor properties (band gaps of about 3.70 eV for 1, 3.49 eV for 2, and 3.89 eV for 3) and photoluminescence properties (emission bands at about 430 nm for 1, 467 nm for 2,and 460 nm for 3).Three dabco/iodoargentate hybrids have been prepared by changing the pH. Variation of the hydrogen-bonded aggregating forms of dabco at different pH, modulation of the inorganic moiety from a [3276] cage in 1 to a [32114] cage in 2 and helical chain in 3, and their intrinsic symmetry/chiral transfer reveal unique dynamic structural directing effects and flexibility of the iodoargentate framework.
Datum: 21.09.2016


Heterotrimetallic CuII(L)–LnIII–MIII (M = Cr, Fe; Ln = Pr, Nd, Sm, Gd) Complexes Ranging from 0D Clusters to 1D Chains and 2D Networks: Syntheses, Structures, and Magnetism

Four heterotrimetallic complexes, {[Cu(L)Pr(H2O)4][Fe(CN)6]}2·2CH3OH·5H2O (1), {[Cu(L)Nd(H2O)4][Fe(CN)6]}2·CH3OH·6H2O (2), {[Cu(L)Sm (H2O)4][Cr(CN)6]·CH3OH·3H2O}n (3), and {[Cu(L)Gd(H2O)3][Fe(CN)6]·CH3OH·0.5CH3CN·2H2O}n [4; L = N,N′-ethylenebis(3-methoxysalicylideneiminato) dianion] were synthesized by a self-assembly method and characterized structurally and magnetically. The results indicate that 1 and 2 are discrete hexanuclear clusters, whereas 3 and 4 form 1D regular chains and 2D networks, respectively. Interestingly, all of the structures possess the same structural inner core of CuII(L)–LnIII–MIII units, which can produce a variety of different structural forms. Magnetic measurements reveal that weak d–f magnetic coupling and the single-ion magnetic effect of the LnIII ions both contribute to the final magnetic behavior. Four new heterotrimetallic CuII(L)–LnIII–MIII (M = Cr, Fe; Ln = Pr, Nd, Sm, Gd) complexes were obtained. Interestingly, the CuII(L)–LnIII–MIII unit forms new discrete hexanuclear clusters, 1D regular chains, and 2D networks, which were not found in related complexes of previous studies.
Datum: 21.09.2016


ZnII and CdII Ferrocenechalcogenolate Complexes

The preparation of the ferrocene-based reagents FcSSiMe3 (1) and fc(SSiMe3)2 (2) [Fc = (η5-C5H5)Fe(η5-C5H4)–; fc = Fe(η5-C5H4)2–] is reported together with their use in the formation of the tetrahedral zinc complexes [(N,N′-tmeda)Zn(SFc)2] (3a) and [(N,N′-tmeda)Zn(S2fc)] (4a), respectively (tmeda = tetramethylethylenediamine). The structures of these coordination complexes are compared to the new ferroceneselenolates [(N,N′-tmeda)Zn(SeFc)2] (3b) and [(N,N′-tmeda)Zn(Se2fc)] (4b), themselves prepared using FcSeSiMe3 and fc(SeSiMe3)2, respectively. The synthesis and characterization of dimeric [Cd2(µ-EFc)2(EFc)2(PPr3)2] (5a, E = S; 5b, E = Se) are also described.Zinc(II) and cadmium(II) complexes ligated with ferrocenethiolates and ferroceneselenolates are readily prepared from substituted ferrocene reagents containing trimethylsilylchalcogen moieties.
Datum: 21.09.2016


Platinum Complexes Bearing a Tripodal Germyl Ligand

The reaction of the germane [Ge(H)(2-C6H4PPh2)3] (1) and the platinum precursor complex [Pt(nbe)3] (nbe = norbornene) gave a racemic mixture of the germyl complex [Pt(nor){Ge(2-C6H4PPh2)3}] (2; nor = exo-2-norbornyl, exo-2-bicyclo[2.2.1]heptyl). Mechanistic studies showed that the hydrido complex [Pt(H){Ge(2-C6H4PPh2)3}] (3) is not formed as an intermediate during the formation of 2. Further studies revealed that in contrast to the chlorido complex [Pt(Cl){Ge(2-C6H4PPh2)3}] (4), the methyl compound [Pt(CH3){Ge(2-C6H4PPh2)3}] (5) is an efficient starting compound for accessing cationic platinum species. Complex 5 was converted into the triflato complex [Pt(OTf){Ge(2-C6H4PPh2)3}] (6) as well as the complexes [Pt(L){Ge(2-C6H4PPh2)3}][B{3,5-C6H3(CF3)2}4] [L = thf (7), toluene (8), CH2Cl2 (9), PPh3 (10)]. A series of five-coordinate platinum(II) complexes bearing the tripodal germyl ligand [Ge(H)(2-C6H4PPh2)3]– is reported. Their structures were studied by X-ray crystallography. The norbornyl complex [Pt(nor){Ge(2-C6H4PPh2)3}] was not formed by the reaction of norbornene with [Pt(H){Ge(2-C6H4PPh2)3}].
Datum: 21.09.2016


High Gas Adsorption Capacity of an agw-Type Metal–Organic Framework Decorated with Methyl Groups

A new methyl-functionalized metal–organic framework, {Cu3(CMPEIP)2·2H2O}n {m-NB13, H3CMPEIP = 5-[(4-carboxy-2-methylphenyl)ethynyl]isophthalic acid} was solvothermally synthesized and structurally characterized. {Cu3(CMPEIP)2·2H2O}n exhibits a high BET surface area of 3215.4 m2 g–1, a large H2 uptake (1.92 wt.-% at 0.1 MPa and 77 K), and excellent CO2 storage capacity (9.24 wt.-% at 0.1 MPa and 298 K).A new methyl-functionalized metal–organic framework, {Cu3(CMPEIP)2·2H2O}n {m-NB13, H3CMPEIP = 5-[(4-carboxy-2-methylphenyl)ethynyl]isophthalic acid} is synthesized and characterized. {Cu3(CMPEIP)2·2H2O}n exhibits a high BET surface area of 3215.4 m2 g–1, a large H2 uptake (1.92 wt.-% at 0.1 MPa and 77 K), and excellent CO2 storage capacity (9.24 wt.-% at 0.1 MPa and 298 K).
Datum: 21.09.2016


C-Silyl-N,N-dialkyl-N′-arylformamidines: Synthesis and Reactions with Phosphorus(III) Chlorides

A method for the synthesis of new C-silyl-N,N-dialkyl-N′-arylformamidines was developed. These derivatives were formed by the deprotonation of N-(trimethylsilyl)formamidinium salts to give the corresponding N-trimethylsilyl carbenes followed by a 1,2-migration of the silyl group. The reactions of C-silylformamidines with phosphorus(III) chlorides were then studied. The reactions between chlorodiphenylphosphane and the C-silylformamidines readily afforded C-phosphanylformamidines in high yields. The reactions of dichlorophosphanes and C-silylformamidines yielded previously unknown phosphanes that feature two formamidine substituents. In the reaction with phosphorus trichloride, the sterically least encumbered formamidine gave a stable two-coordinate compound through the formation of an intermediate tris(phosphane). The reactions of the sterically more encumbered formamidines led to the substitution of only two chlorine atoms to give a chlorophosphane or benzazaphosphole. The structures of key compounds were proven by X-ray crystal structure analyses. A convenient preparative method for the synthesis of C-silyl-N,N-dialkyl-N′-arylformamidines was developed. These derivatives were employed as nucleophiles in reactions with phosphorus(III) chlorides to afford phosphanes that feature one or two formamidine substituents. We were unable to introduce three formamidine substituents into the final product.
Datum: 20.09.2016


Three-Dimensional Co- and Mn-MOFs Containing a C2h-Symmetric Terphenyl-3,3′-dicarboxylate Linker and Their Magnetic Properties

We report herein two new isostructural, three-dimensional (3D) MOFs with the general formula [M(3,3′-tpdc)(dmf)] [M = CoII (I), MnII (II)] resulting from the assembly of a metal ion and the C2h-symmetric ditopic bridging ligand terphenyl-3,3′-dicarboxylate (3,3′-tpdc). Both isostructural MOFs crystallize in the monoclinic space group C2/c. The metal ion is coordinated by four Ocarboxylate (η1:η1:µ2) and two µ2-Odmf atoms in a distorted octahedral geometry. The metal centers are interconnected through bridging 3,3′-tpdc and dmf ligands to form a 1D chain. The resulting 1D metal chains are further interconnected by 3,3′-tpdc ligands to form 3D frameworks without porosity. The thermolabile dmf bridging ligands were easily removed by heating at 180 °C under vacuum for 5 h. The activated MOFs I and II exhibited very low gas uptake of N2, CO2, and H2 after removal of the dmf bridging ligands. The encapsulation of iodine guest molecules by the activated I and II was also investigated. The crystal structure of iodine-encapsulated II was also elucidated. The coordination environment of the MnII atom in II changed as a result of the loss of dmf bridging ligands. The as-prepared MOFs I and II exhibit weak antiferromagnetic interactions in their 1D metal chains; these magnetic interactions should mainly occur between the metal ions bridged by the short carboxylate-based ligand and dmf oxygen atoms. Thermal removal of the bridging dmf molecules led to a change in the Mn···Mn distances in the 1D chains of II that also affected its magnetic properties. Two new magnetically active, isostructural 3D MOFs of general formula [M(3,3′-tpdc)(dmf)] (M = CoII, MnII; 3,3′-tpdc = terphenyl-3,3′-dicarboxylate) have been prepared by employing the C2h-symmetric 3,3′-tpdc bridging ligand. Their gas sorption and magnetic properties have been investigated.
Datum: 20.09.2016


Exploring Structure–Activity Relationships in Synthetic Antimicrobial Peptides (synAMPs) by a Ferrocene Scan

Synthetic antimicrobial peptides (SynAMPs) are an interesting class of novel antibiotic agents used to fight infections caused by resistant bacterial strains. Herein we report the synthesis of a ferrocene-containing lysine (FcLys) suitable for standard Fmoc/tBu solid-phase peptide synthesis. A library of (Arg-Trp)3-based antimicrobial peptides have been synthesized in which all the tryptophan residues were replaced systematically by FcLys and their biological activities evaluated. We call this technique a “ferrocene scan”, in analogy with the well-established “alanine scan” used to investigate crucial interactions in peptides. The FcLys-peptides showed excellent activity against gram-positive bacterial strains compared with the metal-free parent peptide, including a four-fold increase in activity against the resistant bacterial strain MRSA. Moreover, some members of this family of ferrocenoyl peptides also showed an up to 16-fold increased activity compared with the parent peptide against the gram-negative bacterium A. baumannii. This behavior distinguishes these synAMPs from the previously investigated N-terminally ferrocenoylated peptides, which in general showed a dramatically reduced activity against gram-negative bacteria. The FcLys-peptides also showed low hemolytic activity against red blood cells (RBCs), which indicates excellent bacterial selectivity, making them an attractive class of novel peptide-based organometallic antimicrobial agents.A library of ferrocene-substituted antimicrobials with one, two, or even three ferrocene residues in lieu of a tryptophan residue have been synthesized. The most potent compound shows a 16-fold increased activity over the parent, metal-free (RW)3 peptide against the A. baumannii bacteria. A four-fold increase in activity was even observed against a multi-resistant S. aureus MRSA strain.
Datum: 20.09.2016


Nucleation and Crystal Growth of a {V14Sb8O42} Cluster from a {V15Sb6O42} Polyoxovanadate: In-Situ X-ray Diffraction Studies

The hydrothermal transformation of the heteroatom polyoxovanadate compound {Ni(ethylenediamine)3}3[V15Sb6O42(H2O)] · 15H2O in water into [{Ni(en)2}2V14Sb8O42] · 5.5H2O was investigated with in-situ X-ray diffraction experiments at different temperatures. First, the precursor is amorphized very fast and an induction period is observed depending on the reaction temperature. Crystal growth of the product is completed within 3 h, while higher temperatures lead to an accelerated reaction progress. Evaluation of the kinetics demonstrates that heterogeneous nucleation is the rate-limiting step of the reaction. The activation energies for nucleation and crystal growth are very low compared to data reported in literature for several other chemical systems.
Datum: 19.09.2016


Investigating the Structural, Spectroscopic and Electrochemical Properties of [Fe{(EPiPr2)2N}2], E = S, Se, and the Formation of Iron Selenides by Chemical Vapor Deposition

The anionic L, [(EPiPr2)2N]−, E = S, Se, form of the dichalcogenidoimidodiphosphinato type of ligands containing iPr as peripheral groups, has been shown in the past to afford tetrahedral [MIIL2] complexes, E = S, M = Mn, Co, Ni, Zn; E = Se, M = Co, Ni, Zn. The synthesis of the analogous [FeL2] complexes (E = S, complex 1; E = Se, complex 2), was carried out in this work by metathesis reactions between FeCl2 and the corresponding KL salts. For both complexes 1 and 2, X-ray crystallography revealed two distinct molecules in the asymmetric unit. Complexes 1 and 2 are isostructural and exhibit PE and PN bond length differences compared with those of the free ligands, which are translated in shifts of the corresponding IR bands. Cyclic voltametry studies showed that the FeII FeIII oxidation in complex 2 takes place at lower potential compared with that of complex 1. The zero-field Mössbauer spectra of the two complexes are quite similar, providing evidence of similar S = 2 electronic structures. The observation, for both complexes 1 and 2, of crystallographically distinct FeIIE4 sites, is also revealed in the corresponding Mössbauer spectra. Complex 2 was employed as a single source precursor in catalyst-aided Chemical Vapor Deposition experiments, which afforded the formation of the iron selenides FeSe and Fe3Se4.
Datum: 19.09.2016


Lanthanoid complexation by a tris-tetrazole functionalized calix[4]arene

The synthesis and characterization of 5,11,17,23-tetra-tert-butyl-25,26,27-tris(tetrazol-5-ylmethoxy)-28-hydroxycalix[4]arene is reported. Purification of the macrocyle required the use of preparative HPLC techniques. The macrocycle was found to be a poorer ligand for complexation of lanthanoid cations than the bis-tetrazole analogue, but somewhat more effective than the tetra-tetrazole substituted derivative. Two metal complexes of the tris-tetrazole calixarene were structurally characterised. A polymeric sodium salt of the tris-tetrazole calixarene was isolated from a solution containing yttrium and a sodium acetate buffer. A praseodymium complex was isolated in the presence of an ammonium acetate buffer, where the calixarene acts as a unidentate ligand, bound to the metal through one tetrazole-N atom. Increasing the amount of buffer resulted in the crystallisation of a metal-free ammonium salt of the calixarene.
Datum: 19.09.2016


Structural and Electronic Properties of Nb(V), Ta(V), and Pa(V) Fluoride Complexes:The Influence of Relativistic Effects on the Group V Elements

The aqueous fluoro complexes of niobium and tantalum were studied using synchrotron based extended X-ray absorption spectroscopy (EXAFS) as model systems for comparison of the structural and coordination chemistry of the Group V metals Nb, Ta and their pseudo-homologue Pa(V). The EXAFS indicate differences in the coordination chemistry of Nb and Ta in these systems that were not intuitive based on their similar charge and ionic radii. The Ta speciation is dominated by six and seven coordinate fluoro complexes, while the chemical speciation of Nb under the same conditions is dominated by its hydrolyzed oxyfluoride complexes. Quantum chemical computations were performed to more fully describe these observations and these results were compared to our earlier study on the fluoro complexes of protactinium. Computations performed with and without the inclusion of scalar relativistic effects reveal that the differences in the chemistry among the Group V elements, and their pseudo-homologue protactinium, are due to the increasing influences of relativistic effects as Z is increased from niobium to protactinium.
Datum: 19.09.2016


Unusual Aggregation/Gelation-Induced Phosphorescence of Propeller-type Binuclear Platinum(II) Enantiomers

Three binuclear cyclometalated Pt(II) complexes, [(ppy)Pt(u-SA)Pt(ppy)] (ppy = 2-phenylpyridine, SA = salicylaldehyde azine), have been synthesized and characterized. Owing to the blockage of intramolecular rotation of bridging SA ligands, all the complexes exhibit propeller-type enantiomers and aggregation-induced phosphorescence consequently. Interestingly, one complex with -NEt2 groups instead of long alkyl chains, amide, urea peptides, cholesterol, sugar or steroidal groups was found to show strong phosphorescence enhancement gated by the gelation process. This unusual gelation behaviour is rarely encountered, as the metallogel has no any intermolecular hydrogen bonding and Pt-Pt interaction. We contribute the driving forces of gelation behaviour to its propeller-type structure, optimally balanced solubility of -NEt2 groups, enantiomer-induced pi-pi stacking interactions, and strong multiple intermolecular H-C, H-O, and H-H interactions.
Datum: 19.09.2016


Superparamagnetic Core–Shell Metal–Organic Framework Fe3O4/Cu3(btc)2 Microspheres and Their Catalytic Activity in the Aerobic Oxidation of Alcohols and Olefins

Core–shell structured Fe3O4/Cu3(btc)2 (btc = 1,3,5-benzenetricarboxylate) microspheres have been successfully synthesized by coating the metal–organic frameworks on poly(acrylic acid) (PAA) functionalized Fe3O4 microspheres by the layer-by-layer assembly method. The MOF composite exhibited excellent catalytic activity in the aerobic oxidation of alcohols and the epoxidation of olefins due to the porosity of MOFs and large amount of readily accessible Cu2+. Furthermore, the catalyst could be easily segregated from the catalytic system by using an external magnetic field due to its magnetic properties. The heterogeneous catalyst displayed good reusability and broad reagent scope in the aerobic oxidation of alcohols and epoxidation of olefins.Core–shell metal–organic framework Fe3O4/Cu3(btc)2 microspheres have been successfully synthesized by a one-step solvothermal method and a subsequent layer-by-layer strategy. The superparamagnetic heterogeneous catalyst exhibits efficient activity and high selectivity in the aerobic oxidation of alcohols and the epoxidation of olefins. The catalyst shows excellent recyclability.
Datum: 19.09.2016


Prolonging the Emissive Lifetimes of Copper(I) Complexes with 3MLCT and 3(π–π*) State Equilibria – A Fluorene Moiety as an “Energy Reservoir”

Two CuI complexes, [Cu(imPhen)(POP)]PF6 (1, imPhen = 1H-imidazo[4,5-f][1,10]phenanthroline, POP = bis[2-diphenylphosphino]phenyl ether) and [Cu(Flu-imPhen)(POP)]PF6 {2, Flu-imPhen = 2-(9H-fluoren-2-yl)-1H-imidazo[4,5-f][1,10]phenanthroline} were synthesized and characterized. a weak metal-to-ligand charge-transfer (MLCT) absorption band at λ = 401 nm with a relatively low molar extinction coefficient (ε = 3170 m–1 cm–1) was observed for 1. In contrast, 2 displayed a higher MLCT absorption band at λ = 405 nm (ε = 5400 m–1 cm–1) owing to the incorporation of a fluorene group to imPhen ring. Complexes 1 and 2 exhibited similar emission wavelengths and quantum yields (λem = 564 nm, ϕ = 11.2 % for 1 and λem = 568 nm, ϕ = 9.0 % for 2); however, the excited-state lifetime of 2 (τ = 51.2 µs) was almost four times longer than that of 1 (τ = 13.8 µs). The prolonged luminescence lifetime of 2 was rationalized by the reversible energy transfer between the 3MLCT state of the Cu atom and the 3ππ* state of fluorene moiety. To the best of our knowledge, this is the first use of a fluorene group as a triplet energy reservoir to extend the excited-state lifetime of an emissive 3MLCT state of a CuI complex.A fluorene group is used as a triplet energy reservoir to extend the excited-state lifetime of the emissive triplet metal-to-ligand charge-transfer (3MLCT) state of a CuI complex. The excited-state lifetime of the complex with a fluorene moiety (τ = 51.2 µs) is almost four times that of the parent complex (τ = 13.8 µs).
Datum: 19.09.2016


Ferroelectricity in Metal–Organic Frameworks: Characterization and Mechanisms

Ferroelectric metal–organic frameworks are emerging as an exciting field of research and have witnessed great progress in the last decade. In this contribution, we briefly discuss ferroelectricity and its means of demonstration. Three mechanisms that lead to ferroelectricity are identified and critically discussed. On the basis of the shortcomings present in the literature, we present a protocol for the study of ferroelectricity in MOF compounds.Ferroelectric metal–organic frameworks are emerging as an exciting field of research, which has witnessed great progress in the last decade. In this contribution, we briefly discuss ferroelectricity and its means of demonstration. We critically discuss different mechanisms leading to ferroelectricity as well as the state-of-the-art ferroelectric metal–organic frameworks.
Datum: 16.09.2016


Reactivity of CS2 – Syntheses and Structures of Transition-Metal Species with Dithioformate and Methanedithiolate Ligands

The syntheses and structural characterization of the CS2–metal complexes [(η5-C5Me5M)(η2-S2CH2)(η3-S2CH)] (1: M = Mo; 2: M = W), which feature partially and fully reduced CS2, are reported. In addition, the cis and trans isomers of the dimetallic (sulfido)molybdenum complexes [(η5-C5Me5Mo)2(µ-S2CH2S)2] (3-cis and 4-trans) are described. The [Mo2S4] cores of 3-cis and 4-trans represent paddlewheel-like arrays. All the new compounds were characterized in solution by mass spectrometry, IR spectroscopy, and 1H and 13C NMR spectroscopy. Their structural architectures were established by X-ray crystallographic analysis. Quantum-chemical calculations by DFT methods on the model compounds 1′–4′-trans showed good agreement with the experimentally observed structural parameters. The large HOMO–LUMO (HOMO = highest occupied molecular orbital, LUMO = lowest unoccupied molecular orbital) gaps are consistent with the high thermodynamic stabilities of these complexes. Further, the presence of short metal–metal cross-cluster bonds in the X-ray structures of 3-cis and 4-trans is supported by natural bond order (NBO) calculations.We report the syntheses and structures of the CS2-inserted group 6 transition-metal complexes [(η5-C5Me5M)(η2-S2CH2)(η3-S2CH)] (M = Mo, W) and the cis and trans isomers of the (sulfido)molybdenum complex [(η5-C5Me5Mo)2(µ-S2CH2S)2] (Cp* = η5-C5Me5)
Datum: 15.09.2016


Band Gaps and Photocurrent Responses of Bulk and Thin-Film Coordination Polymers Based on 3,6-Di(1H-imidazol-1-yl)-9H-carbazole

From a new rigid N-donor ligand, 3,6-di(1H-imidazol-1-yl)-9H-carbazole (L), two coordination polymers (CPs) formulated as CdL(L1)·3DMF (1; H2L1 = 4,4′-carbonyldibenzoic acid, DMF = N,N-dimethylformamide) and Cu2L2(SO4) (2) were synthesized solvothermally and structurally characterized by single-crystal X-ray diffraction. CP 1 exhibits a two-dimensional (2D) structure, and CP 2 shows one-dimensional (1D) chains. The two CPs exhibit different quasireversible redox properties and possess very weak photoluminescence properties. Density functional theory (DFT) calculations and experimental results show that CP 1 has a wider band gap than that of CP 2. Notably, CP 2 produces a higher photocurrent density than that of CP 1 upon visible-light illumination, which is also in agreement with their Nyquist plots and Mott–Schottky curves. Thin-film CP 1 was obtained by physical exfoliation in methanol and shows more active electrochemical behavior and enhanced photoresponse relative to those of bulk CP 1.From a rigid N-donor ligand, two coordination polymers (CPs) are synthesized. The CdII CP 1 has a 2D structure, and thin-film 1 is obtained by physical exfoliation. The CuI CP 2 possesses a narrower band gap and a higher photocurrent density under visible light than those of 1. Thin-film 1 shows more active electrochemical behavior and enhanced photoresponse relative to those of bulk 1.
Datum: 15.09.2016


A Ferrocene-Based Phosphane/Borane Frustrated Lewis Pair for Asymmetric Imine Reduction

The α-phosphanylferrocenecarbaldehyde (pS)-1 was converted into the β-styryl derivative (pS)-4 by Wittig–Horner olefination. Subsequent hydroboration with Piers' borane [HB(C6F5)2] followed by H2 splitting and crystallization gave the phosphonium/hydridoborate product (pS,R)-5, which was used as a frustrated Lewis pair catalyst for the asymmetric hydrogenation of a series of imines (up to 69 % ee).Asymmetric imine hydrogenation with a ferrocene-based frustrated Lewis pair catalyst was achieved with up to 69 % ee.
Datum: 15.09.2016


Electric field control of magnetic and polarizability properties of cyanide-bridged Fe-Co clusters

We present a new microscopic approach for the description of the effects of an external direct current (dc) electric field in the magnetic, polarizability and spectroscopic characteristics of molecular crystals containing cyanide-bridged Fe-Co clusters as structural units. Besides the interaction with the electric field the model allows for the metal-metal electron transfer, intracluster magnetic exchange and long-range electron-deformational interaction that is taken into account within the mean field approach. It is demonstrated that the external electric field gives an unique possibility of manipulation by the polarizability, magnetic and spectroscopic characteristics of cyanide-bridged Fe-Co clusters.
Datum: 15.09.2016


Mechanistic complications caused by redox equilibration. Ascorbate reduction of a ruthenium(III) complex under low driving force conditions

A detailed kinetic study of the reduction of cis-dichloridobispicolinatoruthenate(III) by L-ascorbic acid that leads to the formation of the corresponding Ru(II) complex, was carried out spectrophotometrically using the stopped-flow technique. The reaction was studied as a function of [AscH2]T, [Ru(III)] and pH. The observed kinetic traces could only be fitted to a three-exponential function, characteristic for three parallel reaction paths. However, an earlier study clearly showed that under the selected experimental conditions only a single complex species is present in solution. The observed complication is suggested to arise from the low driving force of the reaction during which the re-oxidation of Ru(II) by the semi-oxidized L-ascorbic acid, i.e. ascorbyl radical Asc*, accounts for the apparent three exponential behavior of the reaction. A detailed account of different modeling efforts and a comparison with related systems is presented.
Datum: 15.09.2016


A Facile Synthetic Route to a Family of Mn(III) Monomers and their Structural, Magnetic and Spectroscopic Studies.

We report a rapid and facile synthetic route to the synthesis of a family of Mn(III) monomers of general formula [Mn(III)F3(H2O)(L1-6)]·xH2O·yMeOH (where L1 = 2,2'-Bipyridyl, x = 2, y = 0 (1′); L2 = 1,10'-Phenanthroline, x = y = 0 (2′); L3 = 6-Methyl-2,2'-dipyridyl, x = y = 0 (3), L4 = 4,4-Dimethyl-2,2'-dipyridyl, x = 2, y = 0 (4), L5 = 5,5'-Dimethyl-2,2'-dipyridyl, x = 0, y = 0.5 (5) and L6 = 5-Chloro-1,10-phenanthroline, x = y = 0 (6). Magnetic susceptibility and magnetisation experiments have been employed to elucidate the anisotropic D tensor for each family member (ranging from -3.01 cm-1 in 2' to -4.02 cm-1 in 5), while multi-frequency / high-field EPR spectroscopic measurements and subsequent simulations gave similar values for complexes 1' (-4.25 cm-1), 2' (-4.03 cm-1), 4 (-3.90 cm-1) and 5 (-4.04 cm-1). The terminal Mn-F vibrational stretches in 1′-6 have been probed using Raman spectroscopy.
Datum: 15.09.2016


Diversity of POM-based Copper Compounds Obtained from the Same Reaction System

The two simple pathways using metallic copper or copper salts were proposed for obtaining hybrid compounds in mild conditions. The variety of Strandberg- and mixed-metal Keggin-based products (NH4)5n{[Cu(en)2][PMo8V4O40]}n*9nH2O (1), (NH4)4n{[Cu(en)(H2O)][P2Mo5O23]}n*3.5nH2O (2), (NH4)7[PMo8V4O40]*17H2O (3) and (NH4)2n{[Cu(en)2][Cu(en)(H2O)][P2Mo5O23]}n*3nH2O (4) were isolated by varying a composition of the reaction system. A rare four-substituted [PMo8V4O40]7- Keggin anion was obtained. The influence of vanadium source (V2O5, NH4VO3 and (NH4)2V6O16) and copper precursor (metal powder vs. its salts) on the nature of resulting products has been studied. The ex situ EPR study revealed formation of VIV and CuII centers in the reaction mixture during Cu0 dissolution. The obtained compounds have been found to possess electrocatalytic activity in the reduction of iodate and nitrite anions whereas carbon paste electrode modified with compound 4 exhibited a linear current response to L-cysteine. Furthemore, the complex 4 demonstrated rapid and almost complete adsorption of a cationic dye.
Datum: 15.09.2016


Solution Conformation and Self-Assembly of Ferrocenyl (Thio)Ureas

Conformations and (dis)assembly processes of ureas and thioureas are of fundamental importance in supramolecular chemistry, anion binding, or crystal engineering both in solution and in the solid state. For sensing and switching processes a redox-active unit, such as the ferrocene/ferrocenium couple, is especially suitable. Herein, self-assembly processes of redox-active ferrocenyl (thio)ureas FcNHC(X)NHR (X = O, R = Fc 1, Ph 2, alpha-naphthyl 3, Me 4, Et 5; X = S, R = Fc 6, alpha-anthracenyl 7) via hydrogen bonds are reported - both in the solid state and in THF and CH2Cl2 solution. A special emphasis lies on the impact of non-classical intramolecular NH···Fe hydrogen bonds in the organometallic systems on conformation and assembly which is absent in conventional organic (thio)ureas. Furthermore, conformational switching and disassembly of 1-6 is induced by oxidation of 1-6 to the respective ferrocenium cations 1+-6+ (redox-switch).
Datum: 15.09.2016


Imines in the titanium coordination sphere - η¹-imine complexes, sources of azavinylidenes and four membered imine-amido N,N'-Chelates

In titanium-imine complexes the ligand can exhibit several bonding modes. While η²-imine complexes are intermediates in several catalytic transformations and well investigated, we studied the potential of imines to coordinate via the lone pair of the nitrogen by a dative bond to the titanium center. We observed the formation of several bis-η¹-complexes from the reaction of such Schiff bases with titanium(IV)-chloride. Depending on the substitution pattern of the imine, also complexes in the stoichiometry of 1:1 are formed. Particular attention is given to the reaction of imines exhibiting a SiMe₃ group at the nitrogen atom. Titanium complexes of such imines open the access to a remarkable N,N'- bidentate ligand system (4) which can only be obtained in the coordination sphere of the metal and cannot be formed by conventional organic synthesis. In this context we also reacted the imines 2d and 2i with CpTiCl₃(5) to yield the titanaazavinylidenes 6a and 6b which might be useful for further modifications.
Datum: 15.09.2016


Unprecedented Increase in Affinity for EuIII over AmIII through Silica Grafting of a Carbamoylmethylphosphine Oxide-Calix[4]arene Site

Grafting of a carbamoylmethylphosphine oxide (CMPO) calix[4]arene ligand to the silica surface yields an anchored host site that displays an unusual 22.4-fold higher affinity (kD value) for EuIII relative to AmIII. This selective cation recognition is in stark contrast to a more flexible propoxy-tethered CMPO-calix[4]arene site on silica. A grafted CMPO-calix[4]arene site on silica demonstrates affinity for EuIII over AmIII, which is unique when compared with a more flexible propoxy-tethered CMPO-calix[4]arene site as well as all previously reported CMPO-calix[4]arene ligands. The results highlight the importance of rigidity when anchoring sites for cation recognition on solid surfaces.
Datum: 13.09.2016


Group 11 Metal Complexes with Unsymmetrical Bifunctional Ferrocene Ligands

The reactions of two unsymmetrical P^N (L1) and P^P (L2) ferrocene (Fc) ligands towards group 11 metal complexes were studied. Ligand L1 shows different behavior with the three metals. Gold forms mononuclear derivatives with the metal center coordinated to the phosphorus atom, whereas the reactions with silver(I) or copper(I) complexes afford mononuclear or dinuclear compounds in which both donor atoms, phosphorus and nitrogen, are involved in the coordination to the metal center. The reactions of the diphosphine ligand [Fc(CH2PPh2)(PPh2)] (L2) with gold(I), gold(III), silver(I), or copper(I) complexes afford mono-, di-, or trinuclear derivatives. Some homo- and heterodinuclear compounds were obtained through the reactions of the mononuclear gold(III) complex [Au(C6F5)3{Fc(CH2PPh2)(PPh2)}] (6), in which one of the phosphorus atoms is free, with gold(I), gold(III), and silver(I) deriiivatives. Some of these derivatives were characterized by X-ray diffraction analysis. Group 11 metal complexes with asymmetric bidentate phosphine–amine and diphosphine ligands are synthesized. These ligands have rich coordination chemistry and adopt monodentate or bidentate chelating or bridging coordination modes. Heterodimetallic complexes are also prepared.
Datum: 13.09.2016


CLICK N' Sleep: light switch behavior of triazole containing Ru-trisbipyridyl complexes

Abstract: A set of RuII-complexes incorporating triazole subunits are presented. They show a solvent dependent light switch effect. Theoretical calculations revealed the excited states involved in the emission process. The findings are highly important for future design of light switch sensors and suggest a severe restriction for functional photomolecular devices synthesized by CLICK chemistry.
Datum: 13.09.2016


Characterization of Ax[W6I14] as Key Compounds for ligand substituted A2[W6I8L6] Clusters

Ax[W6I14] compounds with A = Na, K, Rb, or Cs are prepared from W3I12 and alkali iodides (AI). Crystal structures were solved and refined for Na[W6I14] and A2[W6I14] compounds with A = K, Rb and Cs on the basis of powder and single-crystal XRD diffraction. All compounds behave stable in air and can be dissolved in polar organic solvents making them valuable precursors for long-needed soluble octahedral [W6I8I6]2- cluster ions. Excitation and emission spectra of solid Na[W6I14] and Cs2[W6I14] are reported as reference systems for photophysically active A2[W6I8L6] compounds (L = inorganic or organic ligand) which can be developed therefrom, as demonstrated for Na2[W6I8(OCH3)6]·8(CH3OH).
Datum: 13.09.2016


The Interaction of 1,1′-Diphosphaferrocenes with Gold: Molecular Coordination Chemistry and Adsorption on Solid Substrates

1,1′-Diphosphaferrocene (1) and its 3,3′,4,4′-tetramethyl (2), 3,3′,4,4′-tetraphenyl (3), octamethyl (4), octaethyl (5) and octaphenyl derivative (6) have been investigated in terms of the suitability of 1,1′-diphosphaferrocenes as adsorbate species for fabricating self-assembled monolayers (SAMs) on gold. Compounds 3 and 6 have been structurally characterised by X-ray diffraction. Complexes [Au(4)2][GaCl4] and [Au2(µ-5)2][FeCl4]2 have also been prepared and are only the second and third examples to date of structurally characterised (1,1′-diphosphaferrocene)gold complexes. [Au(4)2][GaCl4] exhibits intramolecular Au···Fe contacts compatible with FeAu bonding interactions, which have not been described before in ferrocene chemistry. [Au2(µ-5)2][FeCl4]2 exhibits an intramolecular Au···Au contact indicative of aurophilic bonding, leading to a structural motif unprecedented for 1,1′-diphosphaferrocenes. Ultrathin films obtained by chemisorption of the 1,1′-diphosphaferrocenes from solution onto gold substrates have been investigated by X-ray photoelectron spectroscopy and near-edge X-ray absorption fine-structure (NEXAFS) spectroscopy. The results indicate that the surface binding of 1 involves the Fe atom together with both P atoms, whereas in the other cases, surface binding can be realised with just one phospholyl ring. There is no indication of any oxidative decomposition of the adsorbates on the surface. According to NEXAFS spectroscopic results 6 gives rise to SAMs of high orientational order. The binding behaviour of 1,1′-diphosphaferrocenes with gold has been studied in molecular and surface coordination chemistry using pristine 1,1′-diphosphaferrocene and five congeners bearing up to eight alkyl or aryl substituents. Self-assembled monolayers (SAMs) and molecular AuI complexes exhibiting unprecedented intermetallic interactions are described.
Datum: 13.09.2016


Synthesis of Metastable Co4N, Co3N, Co2N, and CoO0.74N0.24 from a Single Azide Precursor and Intermediates in CoBr2 Ammonolysis

Metastable cobalt nitrides Co4N, Co3N, Co2N, and cobalt oxide nitride CoO0.74N0.24 were synthesized by ammonolysis of one single metastable azide precursor, [Co(NH3)5N3]Cl2, in high purity by controlled variation of the reaction conditions (temperature, duration, gas atmosphere, and flow rate). The alternative route towards cobalt nitrides by ammonolysis of CoBr2 proceeds via [Co(NH3)6]Br2 and Co(NH3)2Br2 to exclusively yield Co3N. For Co3N1.1 a complex magnetic behavior is observed: dominating ferromagnetic ordering at low temperatures and a small coercive field of 10 mT. Co2N orders antiferromagnetically below 10 K. Electronic structure calculations [DFT, generalized-gradient approximation (GGA)+U] on CoO0.75N0.25 reveal that the experimentally observed rock-salt structure is less stable than the sphalerite-type polymorph by about 30 kJ mol–1 and possesses an antiferromagnetically ordered ground state.Starting from a single metastable azide precursor, we have established a new synthesis route towards metastable Co4N, Co3N, Co2N, and oxide nitride CoO0.74N0.24 by systematic variation of the reaction parameters. High-quality samples granted access to a deeper insight into the magnetic behavior of such phases.
Datum: 13.09.2016


Growing the Molecular Architecture at Alkynyl(amino)carbene Ligands in Diiron µ-Aminocarbyne Complexes

The diiron µ-aminocarbyne imidoyl complexes [Fe2{µ-CN(Me)(R)}(µ-CO)(CO){C(C≡CR′)=NXyl}Cp2] [R = Xyl, R′ = Ph (1a);[1] R = Xyl, R′ = Tol (1b);[1] R = Me, R′ = Ph (1c); R = Me, R′ = SiMe3 (1d); Xyl = 2,6-C6H3Me2, Tol = 4-C6H4Me] have been prepared by the addition of lithium acetylides to precursors containing a terminal isocyanide ligand. The treatment of 1a–c with CF3SO3CH3 afforded the alkynyl(amino)carbene derivatives [Fe2{µ-CN(Me)(R)}(µ-CO)(CO){C(C≡CR′)N(Me)(Xyl)}Cp2][SO3CF3] [R = Me, R′ = Ph (2a); R = Xyl, R′ = Ph (2b); R = Xyl, R′ = Tol (2c)] in high yields. The reactions of 2b,c with CH3OH/NaBF4, NH2R and NaBH4 led to [Fe2{µ-CN(Me)(Xyl)}(µ-CO)(CO){C(CH=C(Ph)OMe)N(Me)(Xyl)}Cp2][BF4] (3), [Fe2{µ-CN(Me)(Xyl)}(µ-CO)(CO){C(CH=C(Tol)NHR)N(Me)(Xyl)}Cp2][SO3CF3] [R = Et (4a); R = Ph (4b)], and [Fe2{µ-CN(Me)(Xyl)}(µ-CO)(CO){C(CH=CHTol)N(Me)(Xyl)}Cp2][SO3CF3] (5) in yields of 65–80 %. Complexes 3–5 were formed by the selective functionalization of the alkynyl group in 2b,c. Complex 2c reacted with NaCH(CN)2/CH2(CN)2 and NaCH(CO2Me)2 to yield [Fe2{µ-CN(Me)(Xyl)}(µ-CO)(CO){C{N(Me)(Xyl)}CH=C(Tol)C(CN)C(NH2)C(CN)2}Cp2] (6) and [Fe2{µ-C(NXyl)C(C(Tol)=C(CO2Me)2)CN(Me)(Xyl)}(µ-CO)2Cp2] (7) in yields of 65 and 60 %, respectively. All the products were purified by alumina chromatography, alumina being presumably involved in the formation of 3, and characterized by elemental analysis and IR and NMR spectroscopy. The structures of 2b, 3, 5, and 6 were ascertained by single-crystal X-ray diffraction analysis. Diiron complexes containing a bridging aminocarbyne and a terminal alkynyl(amino)carbene ligand undergo selective addition of nucleophiles to the alkynyl moiety to yield a variety of structural motifs.
Datum: 13.09.2016


[SiSxHy]n – Perhydridopolysilathianes: Cross-Linked Thio Analogues of Polysiloxanes

Polysiloxane-analogous Si–S compounds have so far not been reported. Transsilylation reactions of the solid pyridine adduct of HSiCl3 with gaseous Me3Si–S–SiMe3 yielded perhydridopolysilathianes. 29Si NMR, FTIR, and Raman spectroscopy; elemental and thermal analysis; XRD; SEM; and gas-adsorption measurements indicated that the product consists of D-, T-, and Q-units with a composition of ([H2SiS]1.2[HSiS1.5]2.6[SiS2]1.0)n. Formation of the latter is caused by pyridine-catalyzed dismutation reactions. The polymer is mesoporous with a surface area of 187 m2 g–1; furthermore, it is amorphous and insoluble in organic solvents. Perhydridopolysilathianes consisting of D-, T-, and Q-units are formed upon transsilylation reactions involving silane dismutation. The products are mesoporous with a surface area of 187 m2 g–1.
Datum: 13.09.2016


5,6- and 6,6-Membered Palladium(II) Pincer Complexes Based on Functionalized Carboxamides with Ancillary Sulfur and Nitrogen Donors

Novel multidentate ligands have been synthesized by the condensation of 2-(methylsulfanyl)benzoyl chloride with a range of amines bearing ancillary N- or S-donors. In reaction with PdCl2(NCPh)2, the ligands derived smoothly underwent direct cyclopalladation to give pincer complexes with 5,6- or 6,6-membered fused metallocycles. The oxidation of the sulfide ligands with H2O2 afforded the corresponding sulfoxide derivatives which readily formed analogous pincer complexes with the Pd(II) ions. The realization of κ3-S,N,X-coordination (X = N or S) was confirmed based on multinuclear NMR and IR spectral data and, in some cases, X-ray crystallography. An unusual dynamic behavior of 6,6-membered S,N,S-complex based on organophosphorus ligand was additionally studied by ROESY technique. All the palladocycles obtained were tested as precatalysts for the Suzuki cross-coupling of aryl bromides with arylboronic acids which allowed us to evaluate the main structure-activity relationships.
Datum: 12.09.2016


Size-Dependent Self-Assembly of Lanthanide-Based Coordination Frameworks with Phenanthroline-2,9-Dicarboxylic Acid as Pre-Organized Ligand in Hybrid Materials

A family of lanthanide-based inorganic-organic hybrids, [Ce4(PDA)4(H2O)9(SiW12O40)]·6H2O (1),[Nd5(PDA)5(H2O)13(OH)(SiW12O40)]·8H2O (2), [Sm3(PDA)2(H2O)13(OH)(SiW12O40)]·16.5H2O (3), [Dy4(PDA)4(H2O)11(SiW12O40)]·7H2O (4) (PDA: 1,10-phenanthroline-2,9-dicarboxylic acid), has been hydrothermally synthesized utilizing the [SiW12O40]4 Keggin-type anion as building block. Characterization by IR spectra, elemental analysis, TGA and single crystal X-ray diffraction revealed that 1-4 are all coordination polymers with different structural features, due to the lanthanide contraction effect. Compound 1 is composed of cationic layers interconnected by Keggin anions into the third dimension. Compound 2 and 3 are 1D rectangular tube-like and 1D ladder-like coordination polymers, respectively. The Keggin anion appears to play a different role in each of these hybrid structures, since its coordination mode varies between mono-, bi- and tetradentate in compounds 3, 1, and 2, respectively. In compound 4 the Keggin anions only reside in the interspace between two adjacent 2D cationic layers as discrete counterions. Magnetic measurements indicate that compound 4 exhibits frequency dependent ac magnetic susceptibilities indicative of slow relaxation of the magnetization.
Datum: 12.09.2016


Single-Ion Magnets Based on Mononuclear Cobalt(II) Complexes with Sulfadiazine

The already reported monomeric complex Co(SDZ)2bpy (1) and the new ternary complex Co(SDZ)2(6MQ)2 (2) (SDZ = sulfadiazine, bpy = 2,2′-bipyridine, and 6MQ = 6-methoxyquinoline) have been synthesized in order to study their magnetic properties. X-ray diffraction studies indicate that in both compounds the SDZ acts as a bidentate ligand coordinating through the sulfonamide and the pyrimidine N atoms giving rise to a CoN6 coordination sphere. The complexes have been characterized based on elemental analyses, FTIR, UV/Vis spectroscopy, and thermogravimetric analysis (TGA, only for 2). Compounds 1 and 2 have been characterized magnetically, and they show slow relaxation of the magnetization below 9 and 6 K, respectively. Two monomeric cobalt complexes, Co(SDZ)2bpy and Co(SDZ)2(6MQ)2 (SDZ = sulfadiazine, bpy = 2,2′-bipyridine, and 6MQ = 6-methoxyquinoline), have been prepared and characterized. X-ray diffraction studies indicate that in both compounds SDZ acts as a bidentate ligand coordinating through the sulfonamide and the pyrimidine N atoms. The complexes show slow relaxation of the magnetization below 9 and 6 K.
Datum: 12.09.2016


Front Cover: Five Disk-Shaped {MII7} (M = Mn, Fe, Co, Cu, Zn) Clusters and One Capsule-Like {CuII6NaI2} Cluster Assembled from the Same Schiff Base Ligand (Eur. J. Inorg. Chem. 26/2016)

The cover picture shows five disk-shaped {M7} transition metal clusters and one capsule-like {CuII6NaI2} cluster, all supported by the same Schiff base ligand L {H2L = 2-(2-hydroxy-3-methoxybenzylideneamino)phenol}. Strong out-of-phase χ'' signals were observed for [Co7L6] at zero field, suggesting that [Co7L6] might be a single-molecule magnet (SMM). Details are discussed in the article by Y. Li et al. on p. 4134 ff. For more on the story behind the cover research, see the Cover Profile.
Datum: 12.09.2016


Spotlights on our sister journals: Eur. J. Inorg. Chem. 26/2016


Datum: 12.09.2016


Five Disk-Shaped {MII7} (M = Mn, Fe, Co, Cu, Zn) Clusters and One Capsule-Like {CuII6NaI2} Cluster Assembled from the Same Schiff Base Ligand

Invited for the cover of this issue is the group of Yahong Li at Soochow University, Suzhou, P. R. China. The cover image shows five disk-shaped {M7} transition metal clusters and one capsule-like {CuII6NaI2} cluster, whose magnetic properties are studied. We synthesized an {FeII7} cluster; this has rarely been achieved in the past…Read more about the story behind the cover in the Cover Profile and about the research itself on p. 4134 ff.
Datum: 12.09.2016


Hand in Hand: Experimental and Theoretical Investigations into the Reactions of Copper(I) Mono- and Bis(guanidine) Complexes with Dioxygen

Mono- and bis(guanidine) ligands stabilise bis-µ-oxido dicopper(III) complexes. Here, the formation of these complexes has been investigated in detail by means of low-temperature stopped-flow techniques for the monoguanidine 2-[3-(dimethylamino)propyl]-1,1,3,3-tetramethylguanidine (TMGdmap) and the related bis(guanidine) 1,3-bis(N,N,N′,N′-tetramethylguanidino)propane (btmgp). Low-temperature IR studies in solution support the formation of bis-µ-oxido complexes. For both systems, no intermediates on the pathways to the bis-µ-oxido complexes could be detected; this has been explained through extensive DFT calculations. In the first step, the oxygen reduction during the binding to the copper(I) complex to form a superoxido species was studied. In the second step, the full path from superoxido through trans-µ-peroxido to side-on peroxido and finally bis-µ-oxido was modelled for singlet and triplet states. Hereby, a clear picture of the detailed reaction mechanism, which directly correlates with the observed activation enthalpies and reaction orders, was gained. The superoxido formation is rate-determining as pseudo-first order in copper(I) although the bis-µ-oxido formation is observed. The results illustrate the strength of density functional theory for the prediction of the reactivity of real-life systems.The reactions of mono- and bis(guanidine)copper complexes with dioxygen to form bis-µ-oxido complexes have been investigated in detail by means of low-temperature stopped-flow measurements and DFT calculations.
Datum: 12.09.2016


Planar-Chiral Secondary Ferrocenylphosphanes

An efficient way to obtain pure diastereomeric mixtures of C-chiral, P-chiral, planar-chiral ferrocenylphosphanes is demonstrated by ortho-lithiation of enantiomerically pure (SC)-N,N-dimethyl-1-ferrocenylethylamine (Ugi's amine) and reaction with RPX2 [X = Cl, Br; R = tBu, 2,4,6-Me3C6H2 (Mes)]. Four secondary ferrocenylphosphanes [Fe(C5H5)(1-PHR-2-CHR'NMe2-C5H3)] (R' = H, R = tBu (1); R' = H, R = Mes (2); R' = CH3, R = tBu (3); R' = Me, R = Mes (4) were synthesised and characterised. Pure diastereomeric mixtures of 1 and 2, a mixture of the pure major diastereomers of 4 and diastereomerically pure 3 were obtained by column chromatography under nitrogen atmosphere. The formation of amine-borane or phosphane-borane adducts was studied by 11B and 31P NMR spectroscopy. A theoretical study was performed to understand the tendency of 1-4 toward borane adduct formation.
Datum: 09.09.2016


Tin(IV) and antimony(V) complexes bearing catecholate ligand connected to ferrocene. Synthesis, molecular structure and electrochemical properties

New ferrocenyl-containing 3,5-di-tert-butylcatechol Fc-L-CatH2 (2) was synthesized by the condensation of precursor 6-(hydrazоnоmethyl)-3,5-di-tert-butylcatechol 6-(H2N-N=CH)-CatH2 (1) with ferrocenecarboxaldehyde (L is -CH=N-N=CH- group; Cat - 3,5-di-tert-butyl-catecholate, Fc - ferrocene). The exchange reaction between catechol 2 and Ph3SbBr2 in the presence of base (Et3N) in toluene media leads to the formation of triphenylantimony(V) catecholate (Fc-L-Cat)SbPh3 (3) as the main product and ionic bromotriphenylantimony(V) catecholate (Fc-LH-Cat)SbPh3Br (4) containing hydraziniumylidene cation (LH is -CH=NH+-N=CH-) as the biproduct. The change of toluene with THF results in a formation of 4 as a main product with nearly quantitative yield. The exchange reaction of catechol 2 with Ph2SnCl2 and SnCl4 even in the presence of excess base gives anionic catecholate complexes bridged with hydraziniumylidene cation. Complexes (Fc-LH-Cat)SnPh2Cl (5), (Fc-LH-Cat)2SnPh2 (6), (Fc-LH-Cat)2SnCl2 (7) were synthesized. The compounds obtained were characterized by IR, 1H and 13C NMR spectroscopy, elemental analysis and cyclic voltammetry. The molecular structures of 5-7 in crystals were determined by X-ray analysis. The formation of catecholates 4-7 with hydraziniumylidene cation is caused by the intramolecular hydrogen bonding between hydroxyl and imine groups leading to the proton transfer from oxygen atom to nitrogen of hydrazine linker.
Datum: 09.09.2016


Molecular Engineering of Iridium Blue Emitters Using Aryl N-Heterocyclic Carbene Ligands

The synthesis of a new series of neutral Iridium (III) bis(2-(2',4'-difluorophenylpyridine)(1-(2'-aryl)-3-methylimidazol-2-ylidene) complexes is reported. Each complex has been characterized by NMR, UV-Vis, cyclic voltammetry, and the photophysical properties deeply explored. Furthermore, two of the complexes were characterized by single crystal X-ray diffraction. By systematically modifying the cyclometallating aryl group on the N-heterocyclic carbene (NHC) ligand from 2,4-dimethoxyphenyl to 4-methoxy-2-methyl-3-pyridine the energy levels of the Ir complexes were modified to produce new blue emitters with increased HOMO and triplet level energies. OLED devices fabricated with these emitters showed external quantum efficiencies (EQE) in the range of 2.3-3.2% with low turn-on values (3 V) and efficacies up to 6.3%.
Datum: 09.09.2016


Hexaethyltripyrrindione (H3Et6tpd): A Non-Innocent Ligand Forming Stable Radical Complexes with Divalent Transition-Metal Ions

Nickel, palladium, and copper complexes of the tripyrrolic ligand hexaethyltripyrrindione (H3Et6tpd, 1) have been prepared and characterized by UV/Vis and EPR spectroscopy, as well as by single-crystal X-ray structure determination. In all cases the metal ion is coordinated in a distorted square-planar geometry carrying a water ligand at the fourth coordination site. The Et6tpd ligand acts as a radical dianion in all cases. In solution, monomeric species are present in which the open-shell character of the ligand becomes apparent through EPR spectroscopic measurements. In the solid state, the compounds form polymorphs with tightly bonded π–π dimers and chains showing small interplanar distances of 3.191–3.493 Å to one or more neighboring molecules. Magnetic measurements on the complexes confirmed the radical character of the tripyrrindione ligand and revealed strong intermolecular magnetic interactions in these complexes. Radical dianionic is the best electronic description of biomimetic tripyrrindione ligands in the ground state of their complexes with divalent ions of nickel, copper, and palladium. The ligand acquires radical character directly upon aerobic metalation and is reminiscent of the antioxidant role of biological tripyrrindiones (the so-called biopyrrins, e.g., uroerythrin) in living systems.
Datum: 07.09.2016


A Palladium(II) Peroxido Complex Supported by the Smallest Steric N-Heterocyclic Carbene, IMe = 1,3-Dimethylimidazole-2-ylidene, and Its Reactivity by Oxygen-Atom Transfer

Stabilized with an N-heterocyclic carbene ligand of the smallest steric profile, PdII(η2-O2)(IMe)2 (IMe = 1,3-dimethylimidazole-2-ylidene) was synthesized by the direct addition of dioxygen to Pd0(IMe)2. The peroxidopalladium complex with IMe, which was previously available only by computation, was characterized by IR spectroscopy and X-ray crystallography. Moreover, its oxygen-atom-transfer reactivity was elucidated by studying its thermolysis in pyridine at 60 °C to yield 1,3-dimethylimidazol-2-one (IMeO) and its reaction with oxygen-atom-transfer acceptors such as PPh3 and (Me3Si)2. PdII(η2-O2)(IMe)2 (IMe = 1,3-dimethylimidazole-2-ylidene), which is used extensively in computational studies as a standard product of Pd0 oxygenation, is synthesized and its oxygen-atom transfer reactivity studied. Thermolysis of the complex leads to the formation of 1,3-dimethylimidazol-2-one (IMeO), and its reaction with PPh3 and (Me3Si)2 results in Ph3PO and (Me3Si)2O, respectively.
Datum: 07.09.2016


Co-crystallization of Half-sandwich (RM,RC)/(SM,RC)-Diastereomers in Single Crystals

Diastereomer separation by fractional crystallization is the most important method for the resolution of enantiomers in research as well as in industry. Herein we describe two different types of diastereomer co-crystallization, which impede diastereomer separation. - The two diastereomers (RFe,RC)- and (SFe,RC)-[CpFe(Prophos)PPh(OMe)2]PF6, differing only in the metal configuration, form 1:1 co-crystals with a racemate-like lattice. Between the (RFe,RC)- and (SFe,RC)-diastereomers there is an almost-inversion center and the (RFe,RC)/(SFe,RC)-pair repeats as a kind of 'dimer' in the lattice. - Crystallization of a 50:50 diastereomer mixture of (RRu,RC)- and (SRu,RC)-[MeCpRu(Prophos)Cl] gave (RRu,RC)/(SRu,RC) 7:93 co-crystals and another crystallization diastereomerically pure (SRu,RC)-[MeCpRu(Prophos)Cl]. In the co-crystal the 93% component (SRu,RC)-[MeCpRu(Prophos)Cl] dictates the build-up of a conglomerate-like lattice and the 7% component (RRu,RC)-[MeCpRu(Prophos)Cl] has to adopt its M-Prophos chelate ring conformation, although diastereomerically pure (RRu,RC)-[MeCpRu(Prophos)Cl] has a completely different chelate ring conformation.
Datum: 06.09.2016


Influence of the pH over the condensation of tetravalent cerium cations for a Ce - [A-a-SiW9O34]10- association leading to the formation of {Ce6O4(OH)4} core.

The reaction of Na10[-SiW9O34] with the 4f tetravalent cerium cations in aqueous solution in presence of sodium acetate at different pH values leads to the stabilization of three cerium based polyanionic molecular clusters [Ce3(2-OH)3(3-O)(SiW9O34)2]13- (1), [Ce3(2-O)3(SiW9O34)2]14- (2) and [(Ce6(3-O)4(3-OH)4)2(W8O32)(SiW9O34)4]32- (3). Cerium condensation behavior when a pH variation occurs in this kind of association with trivacant polyoxometalates is relatively unknown and needed to be explored.The two compounds 1 & 2 consist of a trinuclear cerium cluster fragment stabilized by two polyoxometalates moieties with a variation of the central cerium cluster from {Ce3(2-OH)3(3-O)} to {Ce3(2-O)3}. The third compound (3) appears much more condensed with two hexanuclear {Ce6(3-O)4(3-OH)4} groups are stabilized by the SiW9O34 moieties and a {W8O32} tungsten ring. This evolution in the cluster size and composition reflects the pH variation used during their synthesis. The molecules have been characterized by single-crystal X-ray diffraction, 183W NMR and 29Si NMR spectroscopy, IR spectroscopy, TGA and SEM/EDX microscopy. The three compounds obtained here give an interesting exemplification of the pH influence over condensation of tetravalent cations and open new route toward the stabilization of polynuclear tetravalent clusters by these nucleophilic O-donors POM species.
Datum: 06.09.2016


Intramolecular Cycloaddition in the (Diyne)iridium Complexes [Cp*Ir(CO)(η2-ArC≡CC≡CAr)]: An Experimental and Computational Study

The diyne complex [Cp*Ir(CO)(η2-ArC≡CC≡CAr)] reacts with two-electron donor ligands to form the iridacyclobutenone [Cp*Ir(L){C(C≡CAr)=C(Ar)C=O}]. Kinetic measurements and computational studies support the proposal that the reaction pathway involves alkyne insertion followed by coordination of the two-electron donor ligand. The diyne species [Cp*Ir(CO)(η2-ArC≡CC≡CAr)] undergoes intramolecular cycloaddition in the presence of two-electron donor ligands to afford iridacyclobutenone complexes. Kinetic measurements and a computational study suggest that the reaction proceeds through an alkyne insertion reaction followed by rate-limiting ligand association.
Datum: 06.09.2016


Asymmetrical 1,3-Bis(heteroazolyl)benzene Platinum Complexes with Tunable Second-Order Non-Linear Optical Properties

A series of cyclometallated platinum(II) complexes bearing an asymmetrical 1,3-bis(heteroazolyl)benzene ligand as well as a chloro or phenylacetylene ancillary ligand have been synthesized and characterized. The N^C^N pro-ligands, (benzoxazolyl)(benzothiazolyl)benzene in complex Pt1 and related compounds, and (benzoxazolyl)(benzimidazolyl)benzene in complex Pt2, were synthesized by a two-step procedure that includes a Pd-catalysed C–H bond-activation reaction. The electronic absorption, luminescence and second-order non-linear optical properties of the novel complexes were investigated experimentally and theoretically (TD-DFT) and compared with those of the known 1,3-bis(benzoxazolyl)benzeneplatinum complex, the non-linear optical response of which has been studied for the first time. All the complexes exhibit green luminescence in dichloromethane solution at room temperature, the nature of the heteroazolyl ligand and/or the substituent on the central phenyl ring having no significant impact on the emission signatures. In contrast, functionalization of the terdentate ligands and the nature of the ancillary ligand (chloride or phenylacetylide) allow modulation of the non-linear optical activity. A new series of cyclometallated platinum(II) complexes bearing an asymmetrical 1,3-bis(heteroazolyl)benzene ligand have been prepared. The N^C^N pro-ligands were synthesized by a two-step procedure that includes a Pd-catalysed C–H bond-activation reaction. All the complexes exhibit green luminescence at room temperature and a strong NLO response that can be tuned by ligand design.
Datum: 06.09.2016


Synthesis and Reactivity of Ferrocenyl-Substituted Allylamine Derivatives

[(2-Ferrocenylvinyl)methyl]dimethylamine (2) was obtained in good yields and with perfect regio- and stereoselectivity by reaction of dimethylmethylideneammonium salts with vinylferrocene. After methylation of amine 2, [(2-ferrocenylvinyl)methyl]trimethylammonium iodide (4) was obtained in high yields and used to transfer the ferrocene-containing allyl group to various amines. By controlling reaction conditions, various linear and branched ferrocenyl-substituted allylamines could be obtained with good yields and selectivities. When anilines were used as substrates against ammonium salt 4, compounds originating from Friedel–Crafts reactions were also obtained, with complete regioselectivity towards the para position.[(2-Ferrocenylvinyl)methyl]trimethylammonium iodide (4) was obtained in high yields in two steps from commercially available compounds and used to transfer the ferrocene-containing allyl group to various amines. By controlling reaction conditions, the selectivity of the reaction could be efficiently modified towards linear or branched ferrocenyl-substituted allylamine isomers.
Datum: 06.09.2016


Well dispersed Fe2O3 nanoparticles on g-C3N4 for efficient and stable photo-Fenton photocatalysis under visible light irradiation

In this study, a highly efficient heterogeneous photo-Fenton system (Fe2O3/g-C3N4 /H2O2/visible light) has been developed. The heterogeneous catalyst Fe2O3/g-C3N4 in this system was successfully prepared by growing Fe2O3 nanoparticles on the surface of g-C3N4. The Fe2O3 nanoparticles could achieve high dispersion on the surface of g-C3N4 and form heterojunction with g-C3N4 to make charge separation improved. In addition, the combination of the the Fenton's reagent Fe2O3/H2O2 and the photocatalyst g-C3N4 greatly enhances the rate of Fenton's reaction with the assistance of the photocatalytic process. The results showed that the Fe2O3/g-C3N4 catalyst had a superior catalytic activity as compared with single component of Fe2O3 or g-C3N4 and the mechanical mixture of Fe2O3 and g-C3N4. The optimal catalyst prepared with 3 ml of FeCl3 aqueous solution shows the best photo-Fenton photocatalytic efficiency with a reaction rate constant of 0.02461 mg L-1 min-1, which is about 45.4, 8.4 and 7.2 times that of pure Fe2O3 (0.0005418 mg L-1 min-1) , pure g-C3N4 (0.00294 mg L-1 min-1) and the mechanically mixed Fe2O3/g-C3N4 (0.0034 mg L-1 min-1), respectively. A possible mechanism on the visible light irradiated photo-Fenton photocatalysis was proposed. And the Fe2O3/g-C3N4 catalyst exhibited stable performance without obvious loss of catalytic activity after four successive runs, showing a good application prospect for the photo-oxidative degradation of organic contaminants in wastewater.
Datum: 05.09.2016


C-N Bond Coupling Reactions of Ammonia with Acetone Promoted by Iridium and Rhodium Complexes: Experimental and DFT Studies

Treatment of acetone solutions of the known chlorido-bridged complexes [{M(m-Cl)(cod)}2] (M = Ir, Rh; cod = 1,5-cyclooctadiene) under an ammonia atmosphere afforded the cationic complexes [M(cod)(kN,kN-NH2-C(CH3)2-CH2-C(CH3)=NH)]Cl (M = Ir (3), Rh (4)). The molecular structures of 3 and 4 showed the formation of six-membered metallacycles due to the presence of a 4-imino-2-methylpentan-2-amino kN,kN-chelated ligand. Alternatively, the cations [M(cod)(NCCH3)2]BF4 (M = Ir, Rh) reacted with gaseous ammonia at atmospheric pressure affording bis ammine complexes [M(cod)(NH3)2]BF4 (M = Ir (5), Rh (6)), which were found to react with acetone forming cations [M(cod)(kN,kN-NH2-C(CH3)2-CH2-C(CH3)=NH)]BF4 (M = Ir (7), Rh (8)). DFT studies reveal that the transformation of 6 - 8 is mediated by NH3 molecules acting as an external base. The reaction is triggered by deprotonation of an ammonia ligand forming a metal-amido intermediate which further transforms to an acetimino ligand via aldol condensation. The terminal methyl group of one acetimino ligand is deprotonated by NH3 yielding an enamine ligand which can react with the imine ligand via concerted nucleophilic addition affording the metallacycle which is stabilized by protonation.
Datum: 05.09.2016


Energetic Materials Trends in 5- and 6-Membered Cyclic Peroxides Containing Hydroperoxy and Hydroxy Substituents

Ten peroxide compounds based upon the 3,6-di(hydroperoxy)-1,2-dioxane, 2-hydroxy-6-hydroperoxy-1,2-dioxane, 3,5-di(hydroperoxy)-1,2-dioxolane, and 3-hydroxy-5-hydroperoxy-1,2-dioxolane skeletons have been synthesized, structurally characterized, and fully evaluated for their energetic materials properties. The solid state structures of these compounds are dominated by hydrogen bonding interactions involving the hydroperoxy and hydroxy groups. Energetic materials testing shows that most of the compounds are highly sensitive toward impact and friction, with similar properties to highly sensitive peroxides such as triacetone triperoxide. 3,5-Diethyl-5-hydroperoxy-1,2-dioxolan-3-ol (3b) and 3,5-dimethyl-5-hydroperoxy-1,2-dioxolan-3-ol (5b) have lower impact and friction sensitivities than the other compounds, with values that are appropriate for use as primary explosives.
Datum: 05.09.2016


Formation of NH,NR N-Heterocyclic Carbene Complexes through Mercuration of Mono-N-substituted Benzimidazoles

A simple two-step method to prepare NH,NR N-heterocyclic carbene (NHC) complexes is described herein. In the first step, the reactions of N-substituted benzimidazoles (R-BimH) with Hg(OAc)2 in the presence of NaBr rendered 12-membered mercuramacrocycles [Hg4(R-Bim)4Br4] [R = Me, pyridyl (Py), Bn]. These complexes consist of four HgII ions bridged by four benzimidazolyl anions through N and C atoms. This reaction presumably proceeds through an initial N-complexation of the benzimidazole to the HgII ion. Consequently, C2-H becomes more acidic, and even an acetate anion can promote the deprotonation at C2 to form the C-metalated products. The second step involves the protonation of these mercuramacrocycles with HBF4·OEt2 to give the protic complexes featuring the NH,NR–NHC ligands of general formula [(R-BimH)2Hg][BF4]2 (R = Me, Py, Bn).The reactions of N-substituted benzimidazoles (R-Bim) with Hg(OAc)2 in the presence of NaBr produces N- and C-bound 12-membered mercuramacrocycles [Hg4(R-Bim)4Br4] [R = Me, pyridyl (Py), Bn]. The further protonation of these mercuramacrocycles with HBF4·OEt2 produced NH,NR N-heterocyclic carbene (NHC) complexes [(R-BimH)2Hg][BF4]2.
Datum: 05.09.2016


Dioxidomolybdenum(VI) Complexes of Tripodal Tetradentate Ligands for Catalytic Oxygen Atom Transfer between Benzoin and Dimethyl Sulfoxide and for Oxidation of Pyrogallol

The reactions of the tripodal tetradentate ONNO donor ligands 6,6′-{[(2-morpholinoethyl)azanediyl]bis(methylene)}bis(2,4-di-tert-butylphenol) (H2L1), 6,6′-{[(2-morpholinoethyl)azanediyl]bis(methylene)}bis(2,4-dimethylphenol) (H2L2) and 6,6′-{[(2-morpholinoethyl)azanediyl]bis(methylene)}bis[2-(tert-butyl)-4-methylphenol] (H2L3) with [MoVIO2(acac)2] (acac = acetylacetonato) in a 1:1 molar ratio in MeOH gave the corresponding cis-dioxidomolybdenum(VI) complexes [MoO2(L1)], [MoO2(L2)] and [MoO2(L3)], respectively, in excellent yields. These complexes were characterized by various spectroscopic (IR, UV/Vis, 1H and 13C NMR), electrochemical, thermogravimetric, single-crystal XRD, and powder XRD (PXRD) studies. In these complexes, the geometry around the cis-[MoO2]2+ core is distorted octahedral, and the ligands are tetradentate and coordinate through two Ophenolate, one Ntripodal, and one Nmorpholine atoms. One of the oxido groups and the morpholine nitrogen atom occupy the axial sites. These complexes were used for catalytic oxygen atom transfer between benzoin and dimethyl sulfoxide (DMSO) in acetonitrile at 80 °C, and the formation of benzil was followed by HPLC. Detailed kinetic studies revealed a first-order rate in benzoin and catalyst, and the rate constant for the second-order oxygen atom transfer reaction was 0.0162 m–1 h–1. The formation of the dinuclear intermediates [LMoV–µ-O-MoVL] was established by MALDI-TOF MS and UV/Vis spectroscopy. Its reversible nature was further supplemented by UV/Vis spectroscopy. These complexes also catalyze the oxidation of pyrogallol in a fashion similar to that of transhydroxylases. Under aerobic conditions, the initially formed oxidation product phloroglucinol undergoes further oxidative coupling in the presence of H2O2 to give purpurogallin as the final product. This process follows Michaelis–Menten-type kinetics with respect to pyrogallol; the kcat values obtained were 394, 300 and 247 h–1 for [MoVIO2(L1)], [MoVIO2(L2)] and [MoVIO2(L3)], respectively. Dioxidomolybdenum(VI) complexes of tripodal tetradentate ligands are isolated. Their characterization and use as catalysts for oxygen atom transfer between dimethyl sulfoxide (DMSO) and benzoin as well as the oxidation of pyrogallol are reported.
Datum: 05.09.2016


Thermal and Magnetic Diversity in the Behaviour of the CuII-bdc-bpa System: 1D, 2D and Interpenetrated 3D Frameworks

Metal organic frameworks (MOFs) are crystalline materials based on connections between metal ions through organic ligands. The combination of polycarboxylate anions and dipyridyl ligands is an effective strategy for producing extended structures. In this sense, the combination of bpa with m-bdc [bpa = 1,2-bis(4-pyridyl)ethane, m-bdc = 1,3-benzenedicarboxylate] has produced three new CuII-based networks with different dimensionalities, namely the 1D [Cu(m-bdc)(bpa)0.5(H2O)dmf]·0.5H2O (1, synthesis based on sonication and slow evaporation), the 2D [Cu6(m-bdc)6(bpa)6(dmf)3]·8dmf (2, microwave synthesis) and the 3D [Cu4(m-bdc)4(bpa)2dmf]·dmf (3, microwave synthesis). The three compounds have been structurally characterized by means of single-crystal X-ray diffraction, IR and UV/Vis spectroscopy and elemental analysis. An unprecedented CuII dimer has been observed for compound 3. The thermal behaviour of the compounds was analysed by thermogravimetry (TG/DSC) and X-ray thermodifractometry (TDX), and it was concluded that the dimensionality plays an important role in their thermal properties. Electronic paramagnetic resonance and magnetic susceptibility measurements for compounds 1 and 3 showed that antiferromagnetic interactions exist between the metal ions.The combination of 1,2-bis(4-pyridyl)ethane and 1,3-benzenedicarboxylate ligands has led to three new CuII-based networks with different dimensionalities, namely the 1D [Cu(m-bdc)(bpa)0.5(H2O)dmf]·0.5H2O, the 2D [Cu6(m-bdc)6(bpa)6(dmf)3]·8dmf and the 3D [Cu4(m-bdc)4(bpa)2dmf]·dmf (bdc = 1,3-benzenedicarboxylate, bpa = 1,2-bis(4-pyridyl)ethane).
Datum: 05.09.2016


Siamese-Twin Porphyrins: Variation of Two meso-Aryl Groups

Variation of two out of the six meso-aryl groups in Siamese-twin porphyrin, an expanded porphyrin incorporating two pyrazole moieties, identified a set of substituents that result in optimized preparation of highly crystalline products. Electron-donating and electron-withdrawing aryl substituents have only negligible electronic and structural influences on the free-base macrocycles (as measured by their UV/Vis absorption spectra and solid-state structures, respectively) and their dicopper complexes (as measured by their cyclic voltammograms).The electronic and structural effects of the variation of two of the peripheral meso-aryl groups of Siamese-twin porphyrins are small to negligible, but because of solubility and crystallinity modulations, the new derivatives have multiple benefits.
Datum: 05.09.2016


Reversible Formation of a Cerium-Bound Terminal Hydride: Ce(C5Me4SiMe3)2(H)(thf)

The use of the bulky cyclopentadienyl ligand Cp′ (Cp′ = C5Me4SiMe3) to stabilize cerium hydrides has resulted in the preparation of two novel tuck-in complexes with C–H activated SiMe3 groups. Subsequent reaction of these with H2 in thf gives a lanthanide terminal hydride species Ce(Cp′)2(H)(thf) which reversibly regenerates the tuck-in complex under sustained vacuum. This compound is only the second structurally characterized terminal cerium hydride. This new hydride is a catalyst in H/D exchange reactions between with both sp3-CH and sp2-CH bonds, and for the hydrogenation of unsaturated alkene bonds. The cerium tuck-in metallocene Ce(C5H4SiMe3)(C5H4SiMe2CH2-)(thf) was synthesized and shown to reversibly form a terminal hydride species Ce(C5H4SiMe3)2(H)(thf) upon reaction with H2. This new hydride is a catalyst in H/D exchange reactions between with both sp3-CH and sp2-CH bonds, and for the hydrogenation of unsaturated alkene bonds.
Datum: 01.09.2016


Synthesis of Lewis Base Adducts of Barium Bis[bis(trimethylsilyl)amide]

Transmetalation of Sn{N(SiMe3)2}2 with barium metal in 1,2-dimethoxyethane (DME) yields [(dme)2Ba{N(SiMe3)2}2] (1). The neutral ether ligand can be substituted by stronger Lewis bases such as tetramethylethylenediamine (tmeda) and pentamethyldiethylenetriamine (pmdeta) leading to the formation of [(tmeda)Ba{N(SiMe3)2}2] (2) and [(pmdeta)Ba{N(SiMe3)2}2] (3). The tetrahydropyran adduct [(thp)3Ba{N(SiMe3)2}2] (4) can be isolated after addition of tetrahydropyran (thp) to coligand-free [Ba{N(SiMe3)2}{µ-N(SiMe3)2}]2. The Ba–N bond lengths to the amido ligands are dictated by the coordination number of the metal atom. A comparitive analysis with alternative methods of preparation shows that the metathetical approach requires the use of exact stoichiometry because bariates form with any excess KN(SiMe3)2.Transmetallation of distillable tin(II) bis[bis(trimethylsilyl)amide] with barium metal guarantees the isolation of highly pure barium bis[bis(trimethylsilyl)amide] with diverse coligands depending on the solvent.
Datum: 01.09.2016


Water-Soluble Platinum(II) Complexes Featuring 2-Alkyl-2H-tetrazol-5-ylacetic Acids: Synthesis, Characterization, and Antiproliferative Activity

2-R-2H-Tetrazol-5-ylacetic acids (abbreviated as 2-R-taa; R = Me, iPr, tBu) react with K2[PtCl4] in 1 m HCl in H2O at r.t. furnishing trans-platinum(II) complexes trans-[PtCl2(2-R-taa)2] (1–3), whereas cis-isomeric species cis-[PtCl2(2-R-taa)2] (R = iPr, 4; tBu, 5) are isolated at lower temperature (4–6 °C). In the presence of EtOH in the reaction mixture, esterification of the tetrazol-5-ylacetoxy group of 2-tBu-taa leads to trans-[PtCl2(ethyl 2-tert-butyl-2H-tetrazol-5-ylacetate)2] (6). Complexes 1–6 were characterized by elemental analyses (CHN), HRESI+-MS, 1H, 13C{1H}, 195Pt{1H} NMR and IR spectroscopy, differential scanning calorimetry/thermogravimetry (DSC/TG), and X-ray diffraction (for 1·H2O, 2, 3·2H2O, 4, 5·2H2O, and 6). The generation of the tetrazole-based complexes in solution (1 m DCl in D2O, 25 °C) was studied by 1H NMR spectroscopy and HPLC-MS. The obtained data indicate the initial formation of anionic [PtCl3(2-R-taa)]– complexes that are subsequently converted into disubstituted isomeric platinum(II) species cis- and trans-[PtCl2(2-R-taa)2]. By contrast to cis- and trans-[PtCl2(2-R-taa)2] that were inactive in two human cancer models in vitro (IC50 > 100 µm), complex 6 demonstrated noticeable antiproliferative effects in HT-29 colon and MCF-7 breast carcinoma cell lines with IC50 values of 14.2 ± 1.1 and 5.8 ± 1.2 µm, respectively.Water-soluble platinum(II) complexes featuring 2-alkyl-2H-tetrazol-5-ylacetic acids have been synthesized and characterized. The generation of the tetrazole-based complexes in solution (1 m DCl in D2O, 25 °C) was studied by 1H NMR spectroscopy and HPLC-MS. Antiproliferative activity of the new tetrazole-containing platinum(II) complexes is discussed.
Datum: 01.09.2016


Chiral and Redox-Active Room-Temperature Ionic Liquids Based on Ferrocene and l-Proline

The syntheses of room-temperature ionic liquids (RTILs) combining the naturally occurring amino acid l-proline and ferrocene (Fc) building blocks are reported. After quaternization of ({[(2S)-N-methylpyrrolidine-2-yl]methyleneoxy}carbonyl)ferrocene (1) with alkyl iodides and anion exchange, the resulting diastereomeric (1S,2S)- and (1R,2S)-[(ferrocenylcarbonyl)oxy]methylene-N,N-dialkylpyrrolidine-1-ium RTILs are redox-active and air- and water-stable. They are also thermally stable up to 263 °C. The electrochemical FeII/FeIII potential is shifted to +0.28 V versus Fc/Fc+. Before anion exchange, several iodide derivatives were obtained as crystalline products, and their crystal structures are reported. According to the NMR spectroscopic data cation–anion aggregates are present in the non-coordinating solvent CDCl3. In contrast, in the polar solvent [D6]dimethyl sulfoxide ([D6]DMSO), the ion pairs are separated. The syntheses of the first ferrocene- and pyrrolidinium-based room-temperature ionic liquids (RTILs) linked through ester bridges are reported. The RTILs are reversibly redox-active through the FeII metal center as well as chiral and thermally stable up to 263 °C.
Datum: 01.09.2016


pH-Controlled Luminescence Turn-On Behaviour of a Water-Soluble Europium-Based Molecular Complex

We have successfully synthesized a new europium metal–organic complex (MOC) [Eu2(pydcH)6]·3H2O (1, H2pydc = 2,6-pyridinedicarboxylic acid) by the hydrothermal technique as well as simple solvent evaporation in water. Single-crystal X-ray crystallographic data of 1 confirms a molecular complex of tricapped trigonal prismatic Eu3+ ions with a free carboxylic acid site of each 2,6-pyridinedicarboxylic acid ligand. Complex 1 is water-soluble and remains stable in a broad pH range of 2–11. Upon excitation at 280 nm 1 shows a characteristic ligand-sensitized metal-centred visible red luminescence. The luminescence of complex 1 can be further enhanced by changing the pH of the solution in the range of 2–6. Besides, the luminescence response is completely reversible in the range of pH 2–6. The mechanism of the pH-dependent luminescence behaviour is successfully explained and supported by UV/Vis absorption and IR spectroscopic experiments. A water-soluble molecular europium complex with acidic functional sites has been synthesized by the hydrothermal technique and a simple solvent-evaporation method. The structure of the complex has been confirmed by single-crystal X-ray diffraction studies. The complex shows pH-dependent luminescence turn-on behaviour and completely reversible luminescence response in the range of pH 2–6.
Datum: 01.09.2016


Azaferrocene-Based PNP-type Pincer Ligand: Synthesis of Molybdenum, Chromium, and Iron Complexes and Reactivity toward Nitrogen Fixation

We have newly prepared and characterized a series of the azaferrocene-based PNP-type pincer ligands and the corresponding molybdenum, chromium, and iron complexes. The stoichiometric and catalytic reactivity of molybdenum-dinitrogen complexes toward nitrogen fixation has been investigated in details.
Datum: 31.08.2016


MoII Cluster Complex-Based Coordination Polymer as an Efficient Heterogeneous Catalyst in the Suzuki–Miyaura Coupling Reaction

The design and preparation of highly active heterogeneous palladium catalysts is attracting ever-increasing attention. In this paper, we report on the self-assembly of palladium centers and an octahedral molybdenum cluster complex bearing phosphine terminal ligands. This leads to a coordination polymer exhibiting high catalytic activity in the Suzuki–Miyaura cross-coupling reaction. The coordination polymer achieved a turnover number of 15800 in a reaction of deactivated aryl bromides with phenylboronic acid. Because metal clusters represent rare building blocks for the preparation of heterogeneous palladium catalysts, this work points to new structural motives that can be utilized to develop highly active heterogeneous catalysts.A novel hexanuclear molybdenum cluster, bearing six phosphine terminal ligands, has been synthesized and its single-crystal structure was determined. The combination of the cluster with PdII centers formed a coordination polymer that displayed high catalytic activity in the Suzuki–Miyaura coupling reaction.
Datum: 30.08.2016


The Dimeric Pyramidal Cu2O6(H2O)2 Unit – A Structural Invariant of a Homologous Series of Copper-Layered Phosphonates

Two new layered copper hybrid materials, namely, the copper thiophene-2,5-diphosphonate [Cu2(H2O)2(O3P–C4H2S–PO3)] (Pnma; a = 7.525 Å, b = 18.292 Å, c = 7.520 Å) and the copper 3-fluorophenylphosphonate Cu(H2O)PO3–C6H4F (P21/c; a = 14.305 Å, b = 7.550 Å, c = 7.479 Å, β = 92.32°), have been synthesized. These compounds belong to the large homologous Cu(H2O)PO3R/[Cu2(H2O)2(O3P–R–PO3)] series, the structure of which is dictated by the presence of isolated dimeric pyramidal Cu2O6(H2O)2 units. The role of the Cu/H2O molar ratio of 1 in the stabilization of such a structure is discussed in connection with the Jahn–Teller effect of the copper cation. The study of the magnetic behavior of polycrystalline samples of the two compounds has revealed antiferromagnetic coupling between the copper ions. The interactions within the dimeric unit were estimated by the Bleaney–Bowers law with the spin Hamiltonian H = –JSCu1SCu2 + gβHS: J = –6.27 cm–1 for [Cu(H2O)PO3]2C4H2S, and J = –6.07 cm–1 for Cu(H2O)PO3–C6H4F.The layered copper phosphonates Cu(H2O)PO3R and [Cu2(H2O)2(O3P–R–PO3)] form a large structural family characterized by the presence of condensed dimeric pyramidal Cu2O6(H2O)2 units. Two new members of this family with R = C6H4F and C4H4S are synthesized. These hybrids exhibit antiferromagnetic interactions between the copper ions that obey the Bleaney–Bowers law.
Datum: 30.08.2016


Extended Sandwich Molecules Displaying Direct Metal–Metal Bonds

Treatment of [Cp*IrCl2]2 (Cp* = pentamethylcyclopentadienyl) with Li[BH3(SePh)] at room temperature led to the isolation of a dimetala analogue of hexaborane(10), nido-[(Cp*Ir)(µ-SePh)2Ir{(Cp*Ir)SePh}B4H8] (1). Solid-state X-ray structure analysis of 1 showed an extended sandwich molecule with two iridium atoms between Cp* and a [B4Ir] ring. Further, in an effort to synthesize the Rh analogue of 1 under similar reaction conditions, we isolated arachno-[{(Cp*Rh)(µ-SePh)3}Rh(µ-SePh)B3H6] (2), a rhodium analogue of tetraboarane(10) in which the {RhB3} unit shows geometric equivalence with a metal π-allyl {MC3} species. Ir complex 1, having an Ir–Ir bond, can be considered similar to the dizinc sandwich complex [Cp*Zn-ZnCp*] in terms of the valence electron count at the metal centers.Treatment of [Cp*IrCl2]2 (Cp* = pentamethylcyclopentadienyl) with Li[BH3(SePh)] at room temperature leads to a dimetala analogue of hexaborane(10), nido-[(Cp*Ir)(µ-SePh)2Ir{(Cp*Ir)SePh}B4H8], and in an effort to synthesize the Rh analogue under similar reaction conditions, arachno-[{(Cp*Rh)(µ-SePh)3}Rh(µ-SePh)B3H6], a rhodium analogue of tetraboarane(10), is isolated.
Datum: 30.08.2016


Induction of Mesomorphism through Supramolecular Assembly in Metal Coordination Compounds of “salphen”-Type Schiff Bases: Photoluminescence and Solvatochromism

Mesomorphism induced by metal (VO2+, Ni2+, Cu2+ and Zn2+) coordination and its influence on the photophysical properties of a new series of symmetric “salphen”-type N,N-bis(4-n-alkoxysalicylidene)-4,5-dichloro-1,2-phenylenediamine ligands (n = 12, 14, 16) bearing highly electronegative spacer substituents and alkoxy arms of varied length have been investigated. The mesomorphism has been probed by polarizing optical microscopy (POM), differential scanning calorimetry (DSC), and variable-temperature powder X-ray diffraction (XRD). The Schiff base ligands are non-mesomorphic; however, coordination to NiII and ZnII ions induces columnar mesomorphism, this being stable down to room temperature in the latter case. Interestingly, the complexes of CuII and VOIV did not show any mesomorphism. The free ligands and the ZnII complexes are luminescent both in the condensed state and in solution, with emission maxima in the condensed state being significantly red-shifted with respect to those in solution. The energy-optimized structure of a representative ZnII complex was ascertained to be distorted square planar in a DFT study employing the GAUSSIAN 09 program. The ZnII and VOIV complexes exhibited solvatochromic effects, showing interesting aggregation behavior in the former case.The effects of metal coordination (M = VO2+, Ni2+, Cu2+ and Zn2+) on mesomorphism and photophysical properties of a new series of salphen ligands have been investigated. The NiII and ZnII complexes show columnar oblique and columnar rectangular phases, respectively, the latter being stable down to room temperature thus affording room temperature mesomorphism. Further, the axial vacant coordination sites in the square-planar ZnII and the square-pyramidal VO(IV) centers facilitate solvatochromism, with the former exhibiting formation of aggregates or monomers in solvents of different coordinating ability.
Datum: 30.08.2016


Superparamagnetic Gadolinium Ferrite Nanoparticles with Controllable Curie Temperature – Cancer Theranostics for MR-Imaging-Guided Magneto-Chemotherapy

A facile polyol approach for preparing low-Curie-temperature (TC) gadolinium-doped iron oxide nanoparticles (GdIO NPs) for targeted magnetic hyperthermia and chemotherapy coupled with T1–T2 dual-model magnetic resonance (MR) imaging (where T1 and T2 are the longitudinal and transverse relaxation times, respectively) is reported. A small amount of Gd doping decreases the TC of iron oxide down to about 400 K. In the presence of ethanolamine, controlled polyol synthesis leads to the formation of low-TC, highly magnetic (52.87 emu g–1), and size-controlled (ca. 10 nm) GdIO NPs. A further conjugation with folate and a chemotherapeutic drug has been developed, and the whole system is used for in vitro magneto-chemotherapy (magnetic hyperthermia and chemotherapy) for cancer treatment. The synthesized GdIO NPs are stable colloids that are hemocompatible and cytocompatible over a wide concentration range and have a high affinity towards cancer cells. The release of a chemotherapeutic drug from the GdIO NPs significantly affects cancer cell viability, and the T1–T2 dual-model magnetic resonance enhances bioimaging in a breast cancer cell model. We suggest that the chemotherapeutic-drug-conjugated GdIO NPs have great potential for cell targeting and magnetic resonance imaging in cancer magneto-chemotherapy. A polyol approach is reported for the easy preparation of low-Curie-temperature (TC) gadolinium-doped iron oxide nanoparticles (GdIO NPs) for targeted magnetic hyperthermia and chemotherapy coupled with T1–T2 dual-model magnetic resonance (MR) imaging (where T1 and T2 are the longitudinal and transverse relaxation times, respectively).
Datum: 30.08.2016


Phenyl vs. Ferrocenyl Cyclometallation Selectivity: Diastereoselective Synthesis of an Enantiopure Iridacycle

Ferrocenyl (Fc) and phenyl (Ph) containing imines FcCH=NCH(R)Ph and FcCH(R)N=CHPh (R = H and Me) were cycloiridated using [Cp*IrCl2]2 with NaOAc in CH2Cl2. All resulted in the formation of neutral chloride ligated half-sandwich iridacycles as a result of ortho-phenyl and not alpha-ferrocenyl C–H activation. The complexes derived from FcCH=NCH(R)Ph (R = H, Me) were obtained as a mixture of E and Z imine isomers, and with R = Me the product obtained from the (S)-imine was isolated by recrystallisation as a single diastereoisomer. The configuration was determined by an X-ray crystal structure analysis as SC,RIr,E.Imines containing both ferrocenyl and phenyl groups undergo selective phenyl C–H activation on cycloiridation with [Cp*IrCl2]2 and NaOAc in CH2Cl2. This was applied to the diastereoselective synthesis of an enantiopure iridacycle of configuration SC,RIr,E.
Datum: 30.08.2016


Determination of the Solubility of Rhabdophanes LnPO4·0.667H2O (Ln = La to Dy)

A systematic study of the solubility of the rhabdophanes LnPO4·0.667H2O (Ln = La–Dy) was performed through oversaturation and undersaturation experiments at different temperatures (298–363 K) to demonstrate the reversibility of the equilibria. The structure of the neoformed phase was controlled carefully over the entire temperature range to enable the unambiguous attribution of the solubility products and the derived thermodynamic data to the rhabdophane phases. The log K°s,0 (298 K) values for LnPO4·0.667H2O ranged from –25.6 ± 0.8 (Pr) to –24.9 ± 1.7 (Eu), and the minimum values were for Pr to Sm, whereas the ΔfG° values at 298 K varied between (–1984 ± 2) and (–2004 ± 2) kJ mol–1 whatever the lanthanide element considered, except for Eu-rhabdophane, which presented the highest Gibbs energy of formation [(–1896 ± 2) kJ mol–1]. From the solubility data obtained at various temperatures, the enthalpies of formation of the rhabdophanes ΔfH° were found to be (–2151 ± 13) to (–2130 ± 12) kJ mol–1, excepted for that of Eu, which reached (–2057 ± 9) kJ mol–1. Solubility experiments are used to determine the thermodynamic properties of the LnPO4·0.667H2O (Ln = La–Dy) rhabdophanes and demonstrate the reversibility of the equilibrium. The variation of the solubility with the ionic radius of the lanthanide is determined. The stability domain of rhabdophanes is more constrained than that of monazites.
Datum: 29.08.2016


Zintl Phases K4–xNaxSi4 (1 ≤ x ≤ 2.2) and K7NaSi8: Synthesis, Crystal Structures, and Solid-State NMR Spectroscopic Investigations

The Zintl phases K4–xNaxSi4 (1 ≤ x ≤ 2.2) and K7NaSi8 are the first representatives of the K–Na–Si system, and both contain tetrahedral [Si4]4– clusters and a charge-balancing number of K+ and Na+ cations. All phases of K4–xNaxSi4 (1 ≤ x ≤ 2.2) crystallize in a new structure type with space group P21/n, as determined by single-crystal X-ray diffraction analysis of the parent phase K3NaSi4. Rietveld refinement of the X-ray diffraction data showed that the solid solutions follow Vegard's rule. K7NaSi8 can only be synthesized by diffusion-controlled reaction of binary precursors and is isostructural with known A7A′T8 (A = Na–Cs; A′ = Li, Na; T = Si, Ge) phases. A combination of solid-state NMR investigations and quantum mechanical calculations served to show the anisotropic chemical bonding behavior of all the atoms in K7NaSi8, which is additionally compared with the related phases A7NaSi8 (A = Rb, Cs).New Zintl Phases: K4–xNaxSi4 (1 ≤ x ≤ 2.2) and K7NaSi8 are the first representatives of the K–Na–Si system. Both compounds contain tetrahedral [Si4]4– clusters that are isolated in K4–xNaxSi4 and connected to form linear [Na(Si4)2]7– dimers in K7NaSi8. Solid-state NMR studies coupled with quantum mechanical calculations revealed anisotropic chemical bonding in K7NaSi8.
Datum: 29.08.2016


On route to C4/C5 P-bifunctional 1,3-thiazole-based NHCs

A facile synthetic protocol enabled to synthesize the C4 phosphanyl-C5-thiophosphanoyl thiazole-2-thione 1 via selective lithiation of the C5-thiophosphanoyl thiazole-2-thione VIb followed by reaction with chlorodiphenylphosphane is presented. Reaction of 1 with elemental sulfur leading to the P(V/V) homo chalcogenide thiazole-2-thione2. Hetero-chalcogenide thiazole-2-thione 4 was achieved via reaction of P(III/V) substituted thiazole-2-thione VIb with H2O2-urea. All compounds were characterized by 31P, 1H, 13C NMR and IR spectroscopy, elemental analyses, mass spectrometry and additionally, by single-crystal X-ray diffraction studies.
Datum: 29.08.2016


Tin(IV) Chalcogenide Complexes: Single Source Precursors for SnS, SnSe and SnTe Nanoparticle Synthesis

A family of tin(IV) bis(hexamethylsilylamide) complexes 2–9 have been synthesized by reaction of [Sn{N(SiMe3)2}2] (1) with the diphenyl dichalcogenanes Ph2E2 (E = S, Se, Te), the radical species TEMPO, or the group 16 elements to form the complexes [(PhE)2Sn{N(SiMe3)2}2] (2–4) and [(TEMPO)2Sn{N(SiMe3)2}2] (5), and [{(Me3Si)2N}2Sn(µ2-E)]2 (6–9) (E = S, 2 & 6; E = Se 3 & 7; E = Te, 4 & 9, E = O2, 9). The isolated tin complexes were characterized by elemental analysis, NMR spectroscopy, and the molecular structures of the complexes were determined by single crystal X-ray diffraction. Thermogravimetric analysis showed complexes 2–4 and 6–8 all to have residual masses close to those expected for the formation of the corresponding “SnE” systems. Complexes 2–4 and 6–8 were also assessed for their utility in the formation of nanoparticles. The materials obtained were characterized by powder X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM) and energy-dispersive X-ray analysis (EDX). Analysis showed formation of SnSe and SnTe from complexes 3–4 and 6–7, respectively.A family tin(IV) bis-HMDS complexes bearing chalcogenide ligands have been synthesized and characterized. Selected complexes have been assessed for their utility in the formation of nanoparticles. Analysis (PXRD, SEM and EDS) showed formation of SnSe and SnTe respectively.
Datum: 29.08.2016


Homo- and Heteroleptic Copper(I) Complexes with Diazabutadiene Ligands: Synthesis, Solution- and Solid-State Structural Studies

The preparation of novel copper(I) complexes of diazabutadiene (DAB) ligands with aliphatic backbones is reported. [Cu(DABR)2](BF4), [Cu(DABR)(NCMe)2](BF4) and [CuCl(DABR)] are easily synthesised and air-stable. These complexes, which remain scarce in the literature, have been fully characterised, and their behaviour both in the solid state as well as in solution has been studied by means of X-ray crystallography, NMR and UV/Vis spectroscopy.The preparation of novel copper(I) complexes with aliphatic diazabutadiene (DAB) ligands is reported. [Cu(DABR)2](BF4), [Cu(DABR)(NCMe)4](BF4) and [CuCl(DABR)] are easily synthesised and air-stable. These complexes, which remain scarce in the literature, were fully characterised, and their behaviour both in the solid state as well as in solution has been studied by means of X-ray crystallography and UV/Vis spectroscopy.
Datum: 29.08.2016


Diastereoselective Synthesis of Dialkylated Bis(phosphino)ferrocenes: Their Use in Promoting Silver-Mediated Nucleophilic Fluorination of Chloroquinolines

The diastereoselective synthesis of dialkylated ferrocenyl bis(phosphane)s bearing aryl, alkyl, and hetero- or polycyclic substituents on the phosphino groups is reported, together with their characterization in the solid state by X-ray structure analysis and in solution by multinuclear NMR spectroscopy. Introduction of various alkyl groups on the ferrocene backbone, namely, tert-butyl, isopropyl, and trimethylsilyl, has a significant influence on the stereoselectivity of the ensuing lithiation/phosphination reactions. Only the introduction of the tert-butyl groups ensures both a high yield and perfect diastereoselectivity, which leads to the exclusive formation of the rac planar chiral tert-butylated diphosphanes. The introduction of electron-rich and -poor phosphorus-based functional groups, namely, furyl-, isopropyl-, cyclohexyl-, phenyl-, mesityl-phosphino, and benzophosphindole, is achieved and gives new alkylated ferrocenyl diphosphanes in moderate to high yields. Investigations are conducted to apply these robust alkylated diphosphanes as auxiliaries in the very challenging palladium-catalyzed nucleophilic fluorination of chloroquinolines at the C–Cl bond. Unexpectedly, a significant favorable effect from the ferrocenyl phosphanes is evidenced by using the commercial AgF reagent for this fluorination that renders any palladium addition useless. This innovative nucleophilic fluorination thus avoids harsh conditions (strictly anhydrous) and highly specialized reagents.The diastereoselective synthesis of dialkylated ferrocenyl bis(phosphane)s bearing aryl, alkyl, and hetero/polycyclic groups on the phosphorus atom is reported together with their characterization by X-ray analysis and NMR spectroscopy. In combination with AgF, these ferrocenyl diphosphanes allow the selective fluorination of 2-chloroquinoline derivatives, whereas palladium is highly deleterious.
Datum: 29.08.2016


Nickel Complexes of Pyridine-Functionalized N-Heterocyclic Carbenes: Syntheses, Structures, and Activity in Electrocatalytic Hydrogen Production

Two bis(benz)imidazolium salts alkylated with pyridyl side arms, H2L1Br2 (1,2-bis{[1-(2-pyridylmethyl)benzimidazolium-3-yl]methyl}benzene bromide) and H2L2Br2 (1,2-bis{[1-(2-pyridylmethyl)imidazolium-3-yl]methyl}benzene bromide) have been prepared and were used as precursors in the synthesis of novel nickel compounds of N-heterocyclic carbenes (Ni-NHCs). The four Ni-NHC complexes [Ni(L1)Br]Br (1a), [Ni(L1)](PF6)2 (1b), [Ni(L2)]Br2 (2a) and [Ni(L2)](PF6)2 (2b) were isolated and characterized by various methods, and the X-ray crystal structures of 1a, 2a and 2b are reported. The nickel ion in 1a is in a square-pyramidal geometry with one of the bromide ions in the apical position, the nickel ions in 2a and 2b are in square-planar geometries. The compounds of the ligand with an imidazole-based carbene revealed much higher activity in electrocatalytic proton reduction and better acid tolerance, although their overpotentials are higher than those of the benzimidazole-based compounds. The presence of bromide ions has an adverse effect on the redox potentials as well as the overpotentials for proton reduction. Complex 2b, having the most planar coordination geometry, appeared to have the highest catalytic efficiency for proton reduction in DMF (ic/ip = 50, kobs = 490 s–1 at 0.1 V/s) when using acetic acid as the proton source. To the best of our knowledge, this is the first report of Ni-NHC complexes that are active in electrocatalytic proton reduction. Pyridine-functionalized Ni-NHC complexes have been prepared and characterized by various methods. The complex having the most planar coordination geometry appeared to have the highest catalytic efficiency for proton reduction in DMF (ic/ip = 50, kobs = 490 s–1 at 0.1 V/s) using acetic acid as the proton source.
Datum: 29.08.2016


A Ru(bipyridine)3[PF6]2 Complex with a Rhodamine Unit – Synthesis, Photophysical Properties, and Application in Acid-Controllable Triplet–Triplet Annihilation Upconversion

A ruthenium(II) tris(bipyridine)–rhodamine triad was prepared to control the triplet-state properties with external stimuli (acid). The rhodamine moiety is an acid-responsive module, and the RuII coordination center is responsible for triplet-state formation upon photoexcitation. Through steady-state UV/Vis absorption and luminescence spectroscopy, electrochemical characterization, and nanosecond/femtosecond transient absorption spectroscopy, we found that the dyad gives a quenched triplet metal-to-ligand charge-transfer (3MLCT) excited state (lifetime τT = 103.6 ns vs. τT = 1.58 µs) in the absence of acid, owing to a photoinduced electron transfer (PET) process. In the presence of acid, the rhodamine unit transforms reversibly from the spirolactam structure into the open-amide structure; thus, the PET is inhibited, the triplet-state lifetime (5.70 µs) is prolonged, and the T1 state is relocated to the rhodamine unit. This is the first time that the fundamental triplet-excited-state properties of a RuII complex, that is, the triplet lifetime and localization, have been controlled simultaneously. Intramolecular singlet–triplet energy transfer and triplet–triplet energy transfer (TTET, 3MLCT3IL) were observed for the triad in the femtosecond and nanosecond transient absorption spectra, respectively. The dyad was used for acid-controllable triplet–triplet annihilation upconversion.A ruthenium(II) tris(bipyridine)–rhodamine triad is prepared, and the switching of the triplet excited state is studied through steady-state and time-resolved transient spectroscopy and electrochemistry. The switch mechanism is based on the acid-activated spirolactamopen-amide transformation of the rhodamine moiety.
Datum: 29.08.2016


Tetranuclear Lanthanide(III) Complexes Containing a Square-Grid Core: Synthesis, Structure, and Magnetism

The reactions of Ln(NO3)3·5H2O (Ln = Dy3+, Tb3+, Ho3+, Er3+) and a multidentate flexible ligand, (E)-N′-[2-hydroxy-3-(hydroxymethyl)-5-methylbenzylidene]-6-(hydroxymethyl)picolinohydrazide (LH4), in the presence of Et3N in a 1:1:3 molar ratio afforded a series of complexes [Ln4(LH2)4(µ2-OH)4]·xCH3OH·yH2O (Dy3+, x = 2, y = 2; Tb3+, x = 4, y = 5; Ho3+, x = 0, y = 13; Er3+, x = 4, y = 6). X-ray diffraction analysis revealed that all the complexes are neutral and possess a distorted [2 × 2] square-grid core [Ln4(µ2-O)4(µ2-OH)4] anchored by the concerted coordination of four doubly deprotonated ligands, (LH2)2–, and four µ2-OH groups. All the Ln centers adopt a distorted triangular dodecahedral coordination geometry. An ac magnetic susceptibility study revealed undulations of the out-of-phase (χM′′) component above 2 K for 1 with a quantum tunnelling of magnetization tail at zero dc field. Surprisingly, a field-induced temperature dependence of the ac frequencies at which the χM′′ maxima occur implies that the slow relaxation is a result of a mixed contribution from more than one Dy3+ center. The reactions of multidentate aroyl hydrazone based ligands (LH4) with Ln(NO3)3 in the presence of triethylamine has afforded a series of tetranuclear complexes [Ln4(LH2)4(µ2-OH)4]·xCH3OH·yH2O (Ln = Dy3+, x = 2, y = 2; Ln = Tb3+, x = 4, y = 5; Ln = Ho3+, x = 0, y = 13; Ln = Er3+, x = 4, y = 6). Detailed analysis of the magnetic data revealed that the Dy3+ analogue is a single-molecule magnet.
Datum: 29.08.2016


Preparation, Characterization, Redox, and Photoinduced Electron-Transfer Properties of the NIR-Absorbing N-Ferrocenyl-2-pyridone BODIPYs

Mono- and di-(N-ferrocenyl-2-pyridone)-containing BODIPYs were prepared using a set of ferrocene-enamine cyclization reactions. The target compounds were characterized by UV-Vis, NMR, and mass spectrometry, while their redox properties were probed by the electrochemical, spectroelectrochemical, and chemical oxidation methods. Redox properties of the di-(ferrocenyl)-containing BODIPY are suggestive of a lack of electronic coupling between the two ferrocene groups. Oxidation of the ferrocene(s) in the target BODIPYs results in their observable fluorescence, while transient absorption spectroscopy data indicate fast electron-transfer from ferrocene donor to the photoexcited BODIPY acceptor. Density functional theory (DFT) and time-dependent DFT (TDDFT) methods were used to elucidate electronic structures of the organometallic BODIPYs and confirm the presence of the low-energy metal-to-ligand charge-transfer states in the NIR region.Mono- and di-(N-ferrocenyl-2-pyridone)-containing BODIPYs were prepared and characterized by a variety of spectroscopic, electrochemical, spectroelectrochemical, and theoretical methods
Datum: 29.08.2016


Resin-Assisted Constructive Synthesis of Spin-Crossover Nanorod Arrays

Spin-crossover (SCO) nanorod arrays have been fabricated by a very simple construction method with cation-exchange polymer resin beads as templates. The nucleation and growth mechanism of the nanorod arrays was studied by SEM. The spin-crossover properties of nanorod arrays with different growth times were characterized by differential scanning calorimetry (DSC), Mössbauer spectroscopy, and magnetic susceptibility measurements. The transition temperatures of the obtained nanorod arrays increase as the immersion time of the nanorods increases. The hysteresis loop widths of these nanorod arrays are larger than that reported for [Fe(Htrz)2(trz)][BF4] (Htrz = 1,2,4-triazole) as bulk powder and nanoparticles. This offers a new route for the fabrication of ordered SCO nanorod arrays by a self-assembly method.Spin-crossover nanorod arrays are synthesized by using cation-exchange polymer resin beads as templates. The nucleation and growth mechanism of the nanorod arrays is explained, and the spin-crossover phenomenon is preserved well in the nanostructured materials.
Datum: 29.08.2016


Enantioselective Synthesis of Ferrocene- or Cymantrene-Fused Planar-Chiral Phospholes

Planar-chiral ferrocene-fused phosphole (S)-1a was prepared in an enantiomerically pure form by enantioselective transformation. The synthesis was started with Kagan's chiral ferrocenyl acetal (–)-2a, and bromo and (Z)-2-bromovinyl substituents were introduced at the 1- and 2-positions of the ferrocene platform in (S)-6a with controlling its planar chirality. The double Li/Br exchange on (S)-6a followed by the reaction with PhPBr2 provided (S)-1a in excellent yield. The structure of (S)-1a was determined by X-ray crystallography. Planar-chiral cymantrene-fused phosphole (S)-1b was also prepared by an analogous asymmetric transformation starting with Jaouen's chiral cymantrenyl acetal (+)-2b.The enantioselective synthesis of planar-chiral ferrocene- or cymantrene-fused phospholes (S)-1a and (S)-1b was achieved. The asymmetric introduced of bromo and (Z)-2-bromovinyl groups at the 1- and 2-positions in (S)-6 followed by the cyclization with PhPBr2 provided (S)-1. The structure of (S)-1a was determined by X-ray crystallography, and derivatization of (S)-1a was examined.
Datum: 29.08.2016


Gold(I)-Catalyzed Reaction of Ferrocene and Propargylic Esters: Synthesis of Functionalized Ferrocene Derivatives

The reaction of propargylic esters with ferrocene in the presence of gold catalysts provided ferrocene derivatives containing a functionalized vinyl moiety. This ferrocene C–H bond functionalization proceeded with complete regio- and stereoselectivity. The reaction was proposed to proceed through electrophilic substitution, in which a vinylgold carbene intermediate arising from 1,2-rearrangement of the starting propargylic ester would behave as the electrophilic counterpart.The Au-catalyzed reaction of ferrocene with propargylic esters provides ferrocene derivatives featuring a functionalized vinyl moiety through initial 1,2-acyloxy rearrangement with generation of a gold carbene intermediate and subsequent electrophilic aromatic substitution. This method demonstrates the potential of carbene intermediates in the C–H bond functionalization of ferrocene.
Datum: 29.08.2016


The Diphosphorus Complex [Cp2Mo2(CO)4(η2-P2)] as a Building Block for the Synthesis of Mixed-Hybrid Coordination Polymers

The three-component reaction of the tetrahedral diphosphorus complex [Cp2Mo2(CO)4(η2-P2)] (1), with Ag[BF4] (2) in the presence of 2,2′-bipyrimidine (3) leads to the formation of the two novel two-dimensional networks 4 and 5. Compound 4 is a new two-dimensional organometallic-organic hybrid polymer, while derivative 5 represents a unique two-dimensional organometallic-inorganic-organic hybrid polymer. These results show the possibility of synthesizing a new class of coordination polymers, which could not be obtained from two-component reactions with organic molecules in addition of metal ions.A three-component reaction of the diphosphorus complex [Cp2Mo2(CO)4(η2-P2)] (Cp = C5H5), Ag[BF4], and 2,2′-bipyrimidine yielded two novel 2D hybrid polymers. One represents a 2D organometallic-organic coordination polymer, while the other is a unique 2D organometallic-inorganic-organic coordination polymer.
Datum: 29.08.2016


A Halogen Bonding 1,3-Disubstituted Ferrocene Receptor for Recognition and Redox Sensing of Azide

A neutral redox-active acyclic halogen bonding (XB) receptor with a ferrocene core functionalised at the 1,3-positions of a cyclopentadienyl ring with iodotriazole motifs is prepared. Owing to favourable host-guest size-complementarity, the receptor was found to be selective for azide over a diverse range of anions with different geometries. Voltammetric studies revealed the unique ability of the XB ferrocene receptor to selectively sense azide via a significant cathodic shift of its ferrocene/ferrocenium redox couple. Notably, much weaker binding of azide was observed for the hydrogen bonding 1,3-bis-prototriazole ferrocene receptor analogue, which also displayed a poorer electrochemical response, suggesting that halogen bonding interactions play crucial roles in the binding and sensing of azide. The first halogen bonding redox-active ferrocene receptor that binds and electrochemically senses azide selectively in solution is reported, which shows greatly improved sensitivity and discrimination compared to its hydrogen bonding analogue.
Datum: 29.08.2016


Iridium(III) Complexes Bearing Chelating Bis-NHC Ligands and Their Application in the Catalytic Reduction of Imines

The IrIII complexes 4 and 5 bearing bis-NHC ligands (NHC = N-heterocyclic carbene) composed of one classical NR,NR NHC and one N,NR NHC donor were prepared by the reaction of the azolium/azole compounds 2I and 3Br, respectively, with [{Cp*IrCl(µ-Cl)}2] (Cp*=η5-C5Me5) in the presence of NaOAc as base. Most likely, the salts 2I and 3Br were first selectively deprotonated at the C2 position of the disubstituted (NR,NR) diazaheterocycle to generate an NHC donor, which then coordinated to the IrIII center. Subsequently, NaOAc promoted C–H bond activation at the pendant imidazole moiety of the intermediate IrIII mono-NHC complexes led to the formation of the six-membered iridacycles 4 and 5, which bear a chelating, doubly C-metalated C(NHC)^C(NHC′) bis-NHC ligand. The IrIII complexes 4 and 5 were tested as precatalysts for the reduction of imines with molecular hydrogen. Moderate to good activity was observed at a catalyst loading of 5 mol-% and an H2 pressure of 3 bar in MeOH.Iridium(III) complexes 4 and 5 bearing C^C bis-carbene chelating ligands composed of a classical NHC and an anionic imidazolylato donor were obtained from imidazolium/imidazole compounds and [{Cp*IrCl(µ-Cl)}2] in the presence of NaOAc. Complexes 4 and 5 are moderately active catalysts in the reduction of various imines with dihydrogen.
Datum: 29.08.2016


An OFF-ON-OFF fluorescent sensor for pH windows based on the 13aneN4: Zn2+ system

The new ligand L was prepared, featuring a 13-membered tetraaza macrocyclic ring and a 1,8-naphtalimide fluorophore appended on a C atom of its backbone. The protonation constants of L as well as its complexation constants with Zn2+ have been determined in 1:1 water:methanol solution by potentiometric titrations. pH-fluorimetric titrations have been carried out both on L alone and in the presence of 1:1 Zn2+ and compared with the % vs pH species distribution. A window-shaped fluorescence trend was observed with pH for the L/Zn2+ system, that behaves as an OFF-ON-OFF pH sensor. The ON window is centered in the 6.5-7.5 pH range, in correspondence with the formation of [ZnL]2+. L also works as a Zn2+ sensor in such pH window, that includes the physiological pH value (7.4). Accordingly, L was used as a probe capable of visualizing the Zn2+ pools in Saccharomyces cerevisiae yeast cells at pH 7.4, with the additional ability of distinguishing between living and dead cells.
Datum: 26.08.2016


Optimal Size-Matching and Minimal Distortion Energy: Implications for Natural Selection by Macrocycle of Iron Species in Heme

In heme, a porphyrin macrocycle naturally selects iron ionic species. It is found that this natural combination is directly related to the geometry sizes of both components. Three series of monostrapped nonplanar metalloporphyrins [M = Fe(III)Cl, Co(II), Ni(II)] and their metal-free counterparts were synthesized as model systems, and their core sizes were compared, and density functional theory computations were used to calculate the molecular distortion energies. The results indicate that optimal size-matching of both is to maintains the minimal distortion energy of the macrocycle. This shows that the mutual selection process between the macrocycle and the metal ion is mainly based on the principle of minimum energy for tuning the electronic structure of the central metal ion; this may be a common principle in natural tetrapyrroles containing metal species. The structural parameters of all the model compounds were directly obtained from their crystal structures.
Datum: 26.08.2016


The Activation of CO2, CS2 and the Formic Acid Dehydrogenation Catalyzed by Iron(II) Hydride Complexes

Fluoroarylimine-stabilized iron(II) hydrides were used for the activation of CO2. The resulting iron(II) formate complex 6, which was obtained by formal CO2-insertion into the Fe-H bond, turned out to be unstable in solution. CO was found to be beneficial for the formation of stable analogues of complex 6. From the three-component reaction of CO, CO2 and iron hydride, a series of stable carbonyl formate iron(II) complexes (7 - 9) was generated. The iron(II) formate complex 6 could also be obtained from the reaction of iron(II) hydride complex with formic acid. Based on this result, the formic acid dehydrogenation reaction catalyzed by iron(II) hydrides was explored. The reaction was monitored by in situ 1H NMR spectroscopy and a possible mechanism was proposed. In addition, iron(II) hydrides could also react with CS2 to generate thiocarboxy iron(II) complexes (12, 13, 14 and 16). An unexpected complex 17 was produced from the three-component reaction of CS2, 4 and compound 15. The possible mechanism of the three-component reaction was also studied through the operando IR monitor.
Datum: 26.08.2016


Synthesis and in vitro toxicity of D-glucose and D-fructose conjugated curcumin ruthenium complexes

A series of carbohydrate conjugated bisdemethoxycurcumin (BDC) ligands were synthesized by using the Huisgen copper(I) catalyzed cycloaddition between azido-functionalized D-glucose and D-fructose as well as propargyl modified BDC. The unprotected sugar ligands were reacted with Ru(bpy)2Cl2 to form curcumin conjugated Ru-complexes of the general formula Ru(bpy)2(L)Cl. Ligands as well as Ru complexes were analyzed by NMR, IR, UV/Vis and fluorescence spectroscopy, mass spectrometry as well as elemental analysis (EA). Incubation of L929, HepG2 and the breast cancer cell line MDA-MB-231 revealed lower cytotoxicity of all carbohydrate conjugated ligands compared to BDC. The Ru-complexes exhibited higher cytotoxicity as the parent ligands in particular against HepG2 cells, whereas the non-cancerous L929 cell line remained unaffected. Unlike expected, the D-fructose conjugated ligand and its corresponding Ru complex did not show any significant toxicity against MDA-MB-231 cells.
Datum: 26.08.2016


Indenyl compounds with constrained hapticity: the effect of strong intramolecular coordination.

A series of cyclopentadienyl and indenyl molybdenum(II) compounds with intramolecularly coordinated pyridine arm, including scorpionate-like species bearing two irreversibly coordinated arms on the indenyl core, was synthesized and characterized. All presented structural types were confirmed by X-ray diffraction analysis. Due to strong nucleophilicity of pyridine, the intramolecular interaction is considerably stronger than in case of analogous species bearing tertiary amines in the side chain. Although the starting compounds for syntheses are isostructural, the reaction outcomes differ considerably. The cyclopentadienyl precursor gives a pentacoordinated 5:N-compound while the indenyl analogue produces a hexacoordinated species with unprecedented 3:N-coordination mode of the indenyl ligand representing an unusual example of so-called indenyl effect. The unusually high stability of the 3:N-coordination compounds toward 3 to 5 haptotropic rearrangement was clarified by theoretical calculations. As the strong intramolecular interaction prevents rotation of the indenyl, it cannot reach the conformation suitable for the 3 to 5 rearrangement. As the result, the low hapticity is effectively locked.
Datum: 24.08.2016


Transition Metal Complexes with Ferrocene-Bridged Bis(imidazolin-2-imine) and Bis(diaminocyclopropenimine) Ligands

The reaction of the ferrocene-bridged bis(imidazolin-2-imine) ligand N,N-bis(1,3-diisopropyl-4,5-dimethylimidazolin-2-ylidene)-1,1-ferrocenediamine, fc(NIm)2, with MCl2 salts furnished the complexes [{fc(NIm)2}MCl2] (M = Mn, Fe, Co, Ni, Cu, Zn), which were structurally and spectroscopically characterized. The iron complex was oxidized by reaction with ferrocenium hexafluoroantimonate, and both compounds, [{fc(NIm)2}FeCl2] and [{fc(NIm)2}FeCl2]SbF6, were further studied by means of Mössbauer spectroscopy, SQUID magnetometry and single-crystal X-ray diffraction, revealing that oxidation occurred at the tetrahedral FeN2Cl2 moiety. The CuX (X = Cl, Br, I) complexes of fc(NIm)2 were synthesized, affording dimeric (X = Cl, Br) or polymeric (X = I) structures. In addition, the ligand fc(NCyp)2, bis(N,N,N',N'-tetraisopropyl-2,3-diaminocyclo-propen-1-ylidene)-1,1'-ferrocene¬diamine, was prepared and the trimetallic complex [{fc(NCyp)2}Pd2Cl4] was synthesized and structurally characterized. The attempted synthesis of the corresponding nickel complex furnished single crystals of the composition [{fc(NHCyp)2}Cl(NiCl3)]; X-ray diffraction analysis afforded the first crystal structure of the [Ni2Cl6]2- anion.
Datum: 24.08.2016


Synthesis, Structure and Gas-phase fragmentation of Trinuclear Mo3S4 Clusters Bearing Aminophosphine Ligands: A Combined Experimental and Theoretical Study

Aminophosphine [Mo3S4X3(edpp)3]+ cluster complexes, 1+ (X=Cl) and 2+ (X=Br) (edpp= 2-aminoethyl)diphenylphosphine) have been quantitatively prepared by reacting the molecular[Mo3S7X6]2- anion with the edpp ligand in a one-pot synthetic procedure. Alternatively, complexes 1+ and 2+ can be synthesized using polymeric {Mo3S7X4}n phases as metal precursors. Their crystal structure show the incomplete cubane-type Mo3S4 cluster core as well as the formation of a unique isomer in which the nitrogen atoms of the amino group and the halide atoms are located above the trimetallic plane. Gas phase reactivity studies on complexes 1+ and 2+ show the subsequent elimination ofneutral HX (X=Cl,Br) molecules under collision induced dissociation (CID) conditions. The fragmentation pattern of 1+ and 2+ in combination with gas-phase DFT calculations are contrary to the general idea on the hemilabile character of the aminophosphine ligands and give support to the formation of unsaturated molybdenum/imine Mo=NH species. Based on DFT calculations, two competitive mechanisms involving a proton transfer from the amino group to a halide ligand attached to the geminal or to the vicinal molybdenum center are proposed. The first mechanism, which is a proton transfer within the nitrogen and halogen atoms bound to the same metal, is energetically favored.
Datum: 24.08.2016


Self-assembly of a tri-lanthanide(III) core sandwiched between two thiacalix[4]arene ligands

Thiacalix[4]arene-p-tetrasulfonate (TCAS) incorporated a tri-lanthanide(III) core to form a 3:2 Ln3TCAS2 complex in aqueous solution. The self-assembly process was monitored at pH 9.5 and 7.4 by HPLC for all lanthanides except PmIII. Self-assembly took place in three steps. First, TCAS and LnIII formed a 1:1 Ln1TCAS1 complex. Second, two molecules of Ln1TCAS1 condensed to form Ln2TCAS2. Finally, Ln2TCAS2 reacted with additional LnIII to form Ln3TCAS2. This self-assembly exhibited extremely slow kinetics and required 1-4 days to reach completion. Small amounts of minor species, including Ln1TCAS1, Ln2TCAS2, and Ln4TCAS2, were observed depending on the LnIII species and pH. The generation of these species is controlled by factors such as the stability of the Ln-TCAS species, effect of coordinated water, and size of LnIII. XAFS spectra of aqueous Gd3TCAS2 solutions established the solution structure of the tri-LnIII cluster sandwiched by two TCAS ligands.
Datum: 24.08.2016


Oxidized Styrylruthenium Ferrocene Conjugates: From Valence Localization to Valence Tautomerism

We report on ferrocenyl styryl ruthenium conjugates FcC6H4CH=CHRu(CO)(PiPr3)2(L) where the electron density at the ruthenium alkenyl site is modified by the variation of coligand L (L = Cl, acac, hfac, or dpvm). Crystallographic studies on three derivatives provide snapshots of the conformational degrees of freedom for rotation around the vinyl-phenylene and the phenylene-ferrocenyl linkages. All four complexes undergo two consecutive, reversible one-electron oxidations, whose potentials depend on the ligand L. According to IR spectroelectrochemistry, the first oxidation of the less electron-rich chloro and hfac complexes is strongly biased towards the ferrocenyl site. The radical cation of the acac complex, however, exists as two equilibrating valence tautomers (VTs) Fc+C6H4CH=CH{Ruacac}Fc[C6H4CH=CH{Ruacac}]+ ({Ruacac = Ru(CO)(PiPr3)2(acac)), where the positive charge is either localized at the ferrocenyl site or delocalized over the styryl ruthenium moiety. Variable-temperature EPR and Mössbauer spectroscopy reveal that the ferrocenium valence tautomer dominates at low T. A marked solvent-dependence on the position and relative intensities of the separate Ru(CO) bands in the IR spectra reveals environmental effects on the relative stabilities of the two VTs, while the strong negative solvatochromism of the prominent near IR band of the radical cation of the acac complex argues for a sizable (intervalence) charge-transfer component of the underlying excitation.
Datum: 24.08.2016


Unexpected Formation and Crystal Structure of the Highly Symmetric Carbanion [C(SiCl3)3]-

Disproportionation reactions of Si2Cl6 in the presence of [n-Bu4N]Cl in halogenated solvents yield the compound [n Bu4N][C(SiCl3)3] (1). The X-ray structure analysis of 1 proves the existence of a planar carbanion, which is stabilized by three trichlorosilyl groups. Quantum chemical analysis shows the presence of highly polar bonds in the anion. Planarization of the anion can be explained by interaction of the occupied lone pair at the carbon atom with the antibonding * orbitals of the Si-Cl bonds (negative hyperconjugation).
Datum: 23.08.2016


Self-assembled palladium and platinum coordination cages: Photophysical studies and anticancer activity

Self-assembled coordination cages are interesting as drug delivery systems. Therefore, the synthesis of new ML (M = Pd, Pt) molecular cages, derived from highly fluorescent, rigid polyaromatic ligands is reported and the first PtL cage with a ligand consisting of three pyridine moieties is described. Photophysical properties were examined showing high quantum yieldsof up to 48% for the methoxy-functionalized ligands. Coordination of the ligands to palladium and platinum ions reduces the metallocages' fluorescence, however. The host-guest chemistry of the palladium cage with cisplatin is investigated confirming the encapsulation. The cages encapsulating cisplatin show a significantly increased cytotoxicity towards A549 (human lung adenocarcinoma) cells compared to cisplatin, and thus appear to be promising delivery vectors for the anticancer drug cisplatin.
Datum: 23.08.2016


Capillary Zone Electrophoresis as a Tool to Monitor the Stability and Hydrolytic Equilibria of Strandberg-Type Polyoxometalates in Aqueous Solution

In this study, we applied capillary zone electrophoresis (CZE) to investigate the solution stability and equilibria of pentamolybdobis(phenylphosphonate), [(C6H5PO3)2Mo5O15]4–, which is a Strandberg-type of polyoxometalate (POM) with considerable promise as an antiviral and anti-HIV chemotherapeutic agent. This is achieved by analyzing the intensities and shapes of the three peaks in the CZE electropherogram that correspond to the three components involved in the equilibria, that is, [(C6H5PO3)2Mo5O15]4–, [Mo7O24]6–, and [Mo8O26]4– anions. The dependence of the equilibria of pentamolybdobis(phenylphosphonate) on various conditions, including sample concentration, counterion, and solution pH, was investigated through CZE. The interactions of pentamolybdobis(phenylphosphonate) with amino acids and cyclodextrins in solution were also investigated and discussed on the basis of the CZE results. Our study indicates that CZE has great potential as a simple, low-cost, and efficient method to monitor the synthesis, purity, stability, and solution equilibria of POMs.Capillary zone electrophoresis is used to monitor the effects of sample concentration, counterion, and solution pH on the stability and equilibria of pentamolybdobis(phenylphosphonate).
Datum: 22.08.2016


A new 3D Cu(II)-based energetic MOF: Synthesis, structure and energetic performance

A new energetic MOF, [Cu2(TO)(DNS)(H2O)]n (1) (H2TO = 1,2,4-triazole-5-one, H2DNS = 3,5-dinitrosalicylic acid), has been synthesized and structurally characterized. Single crystal X-ray diffraction indicates that 1 possess compact 3D architecture. Noteworthily, two oxygen atoms of nitryl coordinate to two Cu(II) ions with syn-anti mode, which is further decrease the sensitivity but no influence on the explosive property. Based on TG and DSC analyses results, a rapidly thermal decomposition process and superior thermostability exist in 1. The non-isothermal kinetic for exothermic process of 1 is studied by Kissinger's and Ozawa's methods. The sensitivity tests and calculated detonation property show that 1 can be used as potential green explosives.
Datum: 22.08.2016


Multiferrocenyl Cobalt-based Sandwich Compounds

The reaction of FcCC-CCFc (Fc = Fe(5-C5H4)(5-C5H5)) (1) with Co(5-C5H5)(CO)2 (2) afforded ferrocenyl-functionalized cyclobutadiene and cyclopentadienone cobalt(I) compounds as well as multiferrocenyl benzene derivatives. The synthesis procedures are described. Eleven products could be separated by column chromatography and were characterized by NMR, UV-Vis and IR spectroscopy, high resolution ESI-TOF mass spectrometry and elemental analysis. For five representatives the structure in the solid state was determined by single X-ray structure analysis. The electronic properties of the appropriate compounds were studied using cyclic and square-wave voltammetry. Further investigation of the interaction between Fe(II)/Fe(III) centres in the mixed-valent species was achieved by in situ UV-Vis/NIR spectroelectrochemistry. These measurements demonstrated that weak electronic metal-metal interactions through the cobalt- coordinated cyclobutadiene building block occur (weakly coupled class II systems according to the classification of Robin and Day), while the cyclopentadienone core acts as insulator (class I) and hence only electrostatic interactions are characteristic.
Datum: 22.08.2016


Synthesis, Electronic Spectroscopy, Photophysics and Electric Properties and X-ray Molecular Structures ofthe Aza Ligands tetrakis[4-(benzoyloxy)phenyl]porphyrinatoComplexes

The synthesis of the new meso-porphyrin namely, tetrakis[4-(benzoyloxy)phenyl]porphyrin (H2TPBP), the meso-(tetrakis[4-(benzoyloxy)phenyl]porphyrinato)zinc(II) starting material complex [Zn(TPBP)] (1) and the 1,4-diazabicyclo[2.2.2]octane (dabco), pyrazine (pyz), 4,4'-bipyridine (4,4'-bpy), 4,4'-diaminodiphenylmethane (4,4'-mda) and the 4-cyanopyridine (4-CNpy) coordination compounds with the TPBP porphyrinate complexes (1-7 respectively) are described. The pyrazine derivative crystallizes as bis-pyrazine six-coordinated zinc metalloporphyrin (4). Complex 5 is present in solid state as a dimer with the 4,4'-bpy acting as a bridging ligand while in solid state, the 4,4'-mda species (6) is a five-coordinated monomer zinc derivative. All structures of 2-6 possess cavities with different dimensions where are located the solvent molecules. The solution UV/Vis spectra of 2-7 exhibit redshifted Soret bands indicating that these derivatives in solution are five-coordinated zinc(II) porphyrin complexes. The proton NMR of these species also confirms this deduction. The photophysical proprieties of 1-7 are similar to those of zinc(II) meso-porphyrins related species. The cyclic voltammetry of the H2TPBP free base and 1-7 present a third one-electron reversible oxidation wave. Single-layer diode devices of the [iridium tin oxide / zinc porphyrins (1-7) / aluminum] configurations show relatively low turn-on voltages.
Datum: 22.08.2016


Multi-Ferrocenyl Aryl Ethers - Applying the Nucleophilic Aromatic Substitution Reactions on Aryl fluorides

The reaction of ferrocenol (FcOH; Fc = Fe(C5H5)(C5H4) with aryl fluorides ArH6-nFn (n = 3 - 6) within a nucleophilic aromatic substitution reaction (SNAr) gave ferrocenyloxy-substituted fluoro benzenes of general type C6H0-3F1-5(OFc)1-5. For 1,3,5-C6H3F3 one, for 1,2,4,5-C6H2F4 two and for C6H6-nFn (n = 5,6) three F atoms could be replaced by FcO units. The reaction of 1,4-(OFc)2-C6F4 with additional amounts of FcOH afforded the tetra- and penta-substituted arenes 3,6-F2-C6(OFc)4 and C6F(OFc)5. Electrochemical investigations of both compounds showed four or five Fc/Fc+ related reversible redox processes that were attributed to electrostatic interactions. The addition of C6F6 as the electrophile after the anionic phospho-Fries rearrangement of a ferrocenyl phosphate (1,3-O->C migration) to the 1,2-substituted ortho-phosphonato ferrocenol, resulted in the formation of the respective ortho-functionalized ether. The constitution of all compounds was verified by using 19F NMR spectroscopy. Steric hindrance of the ortho-substituent resulted in a doubling of the signal sets for the C6F5 moiety in the 13C{1H} and 19F NMR spectra. The identity and substitution pattern of five compounds could also be determined by using single crystal X-ray diffraction analysis, revealing the 1,4-constitution of double functionalized derivatives, intermolecular non-classic C-HF interactions andinteractions.
Datum: 22.08.2016


Octaammine EuII and YbII Azides and Their Thermal Decompositions to the Nitrides

The common preparation for many nitrides is the synthesis from the corresponding metals and nitrogen at quite high temperatures and/or high pressures. Here we present a route to metal nitrides by the use of ammine metal azides under relatively mild conditions. Europium(II) and ytterbium(II) azides are prepared in liquid ammonia at –36 °C in form of their temperature-sensitive octaammine complexes. These were investigated by single-crystal X-ray diffraction at low temperatures, and their structures seem to be the first evidence for the existence of homoleptic ammine EuII and YbII complexes, as well as that the coordination number of these divalent cations can go beyond six with NH3 ligands. In one of the cases presented here the observed coordination polyhedron is better described as a bicapped trigonal prism (C2v), in one case better as square-antiprismatic (D4d). Warming of these compounds to room temperature leads to the lanthanoid metal azides still containing approximately 1 equiv. of ammonia. The behaviour of these azides towards further heating was investigated: By very careful and slow decomposition, the nitrides of europium(III) and ytterbium(III) are obtained at only 230 °C at ambient pressure. This method may be suitable to obtain other metal nitrides at remarkably low temperatures and pressures. EuII and YbII azides are prepared in liquid NH3 at –36 °C in form of their temperature-sensitive octaammine complexes. We present the first evidence for the existence of homoleptic octaammine EuII and YbII complexes. Warming of these compounds to room temperature leads to the lanthanoid metal azides still containing approximately 1 equiv. of ammonia. By slow thermal decomposition, EuN and YbN are obtained at only 230 °C at ambient pressure.
Datum: 22.08.2016


Dyads and Triads based on Phenothiazine, Bisterpyridine Ruthenium(II) Complexes and Fullerene

We report the modular synthesis of donor-photosensitizer-bridge-acceptor (D-P-B-A) triads and D-P dyads for the formation of photoinduced charge-separated species. The structures are based on a phenothiazine unit (D), a bisterpyridine ruthenium(II) complex (P), several phenylene(ethynylene)-type spacer units (B) and a pyrrolidino[60]fullerene (A) entity. The donor-acceptor distance is between 18 to 37 Å and was varied by four different bridging units. The photophysical and electrochemical characterization revealed certain interactions between the active moieties in the ground and the excited state. In particular, a reduced ruthenium-based emission in the triads indicates the occurrence of a quenching process mediated by the fullerene entity. Strong electrostatic interactions between the ruthenium(II) complex and the pyrrolidino[60]fullerene have been observed for the shortest triad, resulting in the strongest electron-accepting pyrrolidino[60]fullerene unit in the series.
Datum: 18.08.2016


Exploring the Nature of the Nanocavity and Channels in Apoferritin and Apoferritin–Sodium Dodecyl Sulfate Complex Using an Enhanced Antenna Effect through the Encapsulation of EuIII–Tetracycline

The drug tetracycline hydrochloride (TC), which has cytotoxic and cytostatic effects on tumor cells, has been encapsulated within the nanocavity of apoferritin in the form of its EuIII complex (Eu3TC). The Eu3TC complex was encapsulated within apoferritin through disassembly followed by reassembly of the protein and exhibited significantly enhanced EuIII emission in comparison with that of free Eu3TC in aqueous buffer at pH 8. The steady-state and transient measurement of the emission of each species in the ternary system suggest that the effective sensitization of EuIII emission may be ascribed to a comparatively rigid environment for the bound TC after encapsulation that promotes efficient energy transfer to the EuIII ions. Emission studies in D2O revealed that the microenvironment of the EuIII ion is shielded from O–H oscillators in the ternary system, and the extent of shielding is greater after the encapsulation of the complex within the apoferritin cavity. The rotational correlation time (θc) of bound TC and docking studies also support the contention that the TC is in a more buried environment after encapsulation within the apoferritin cavity. A competition study with sodium dodecyl sulfate (SDS) revealed that SDS does not interfere with the binding of TC to apoferritin. The biocompatible system consisting of Eu3TC encapsulated within the cavity of apoferritin may be used as an efficient targeted drug transporter, and the sensitization of the EuIII emission may also enable its use as a biosensor.The drug tetracycline (TC) as Eu3TC is encapsulated within the nanocavity of apoferritin through disassembly then reassembly of the protein and exhibits significant enhancement of the EuIII emission in comparison with that of free Eu3TC in aqueous buffer at pH 8. This simple system with Eu3TC encapsulated within the cavity of apoferritin may be used for efficient targeted cancer therapy.
Datum: 16.08.2016


Reactions of the Lithiated Diphosphine tBu2P–P(SiMe3)Li with [(η6-C6H6)RuCl2]2 in the Presence of Tertiary Phosphines

tBu2P–P(SiMe3)Li reacted with [(η6-C6H6)RuCl2]2 at –40 °C in the presence of PR3 (PR3 = PEt3, PEt2Ph, PEtPh2) by the nucleophilic addition of the tBu2P–P(SiMe3) moiety to the benzene ring to yield solely the complexes [(R3P)2Ru(Cl){η5-C6H6(Me3SiP–PtBu2)}] (1). These products decomposed slowly at ambient temperature to yield benzene, Ru clusters, and small amounts of the dinuclear ruthenium complexes [{(R3P)2Ru}2(µ,η2:2-P2)2Ru(PR3)2] (Ru–Ru) (6). Single-crystal X-ray diffraction studies of [(PhEt2P)2Ru(Cl){η5-C6H6(Me3SiP–PtBu2)}] (1b) and [(Ph2EtP)2Ru(Cl){η5-C6H6(Me3SiP–PtBu2)}] (1c) revealed that the addition of the tBu2P–P(SiMe3) group occurred through an exo pathway. Complex 6a (R = Et) displays a planar rectangular P4 system consisting of two P2 units and a Ru–Ru distance that lies in the range of a single bond.Nucleophilic addition to a coordinated benzene ring. tBu2P–P(SiMe3)– attaches to the benzene ring in [(η6-C6H6)RuCl2]2 in the presence of a tertiary phosphine to form unstable [(Et3P)2Ru(Cl){η5-C6H6(Me3SiP–PtBu2)}]. This complex decomposes to give dimeric Cl-bridged RuII complexes together with several phosphorus compounds. In the presence of tBu2P–P(SiMe3)Li it yields [{(Et3P)2Ru}2(µ,η2:2-P2)2].
Datum: 16.08.2016


Structure and Antiferromagnetism of Trinuclear Heterometallic Strings Containing MnII–MII–MnII Frameworks (M = Ni, Pd, Pt)

The syntheses, crystal structures, and magnetic properties of three trinuclear, symmetric, heterometal string complexes stabilized by four dipyridylamide (dpa) ligands were explored. MnNiMn(dpa)4Cl2 (1), MnPdMn(dpa)4Cl2 (2), and MnPtMn(dpa)4Cl2 (3) were found to exhibit an approximate D4 symmetry and a linear metal framework helically wrapped by four syn–syn-type ligands. The center metal ions bond with the amide part of dpa– in a square-planar environment, and the outer Mn ions bond with Cl– and the pyridyl part of dpa– in a square-pyramidal environment. The magnetic susceptibilities of these three compounds showed antiferromagnetic interactions (2J = –13.7 cm–1 for 1, –29.7 cm–1 for 2, and –66.2 cm–1 for 3 in the Heisenberg exchange framework) between the MnII magnetic centers. The value of 2J increased with increasing atomic number of the central metal ion. The antiferromagnetic properties were further confirmed by electron paramagnetic resonance spectroscopy studies in variable-temperature measurements.MnMMn(dpa)4Cl2 (M = Ni, Pd, Pt; dpa = dipyridylamide) shows antiferromagnetism and special electron paramagnetic resonance (EPR) spectroscopy patterns. The antiferromagnetic interaction increases with increasing atomic number of the central metal ion. The antiferromagnetic properties are further confirmed in the EPR studies in variable-temperature measurements.
Datum: 16.08.2016


Photoactivated functionizable tetracarbonyl phenylpyridine manganese(I) complexes as CO-releasing molecules: a direct Suzuki-Miyaura cross-coupling on a thermally-stable CO-RM

A new class of carbon monoxide-releasing molecules (CO-RMs) are reported based on a previously known tetracarbonyl phenylpyridine manganese(I) motif.A pre-functionalized CO-RM undergoes a direct Pd-catalysed Suzuki-Miyaura cross-coupling with phenylboronic acid to give a -extended three-ring CO-RM. Cross-coupling conditions were modified to allow coupling of a morpholine-containing boronic acid on to a CO-RM, introducing drug-like functionality. An LED system was used to facilitate controlled CO-release. Irradiation using an LED (400 nm or 365 nm) gives rise to faster CO-release, with lower overall input power compared to traditional use of a TLC lamp (365 nm), as measured by an assay based on the conversion of deoxymyoglobin to carbonmonoxymyoglobin.
Datum: 16.08.2016


Zinc chloride complexes with aliphatic and aromatic guanidine hybrid ligands and their activity in the ring-opening polymerisation of D,L-lactide

The synthesis of the new hybrid guanidine ligands TMGdmab, DMEGdmab, TMGdeab and DMEGdeab is reported. These ligands were combined with zinc chloride and the four new obtained complexes were structurally characterized by X-ray crystallography and NMR spectroscopy. Furthermore, eight new zinc chloride complexes were obtained by reaction of the hybrid guanidine ligands TMGdmae, DMEGdmae, TMGdeae, DMEGdeae, TMGdmap, DMEGdmap, TMGdeap and TEGdeap. All twelve complexes possess a tetrahedral coordination geometry. The donor situation between guanidine and amine donors was evaluated using density functional theory. These complexes show robust activity in the melt polymerization of technical unsublimed lactide. For selected complexes kinetic polymerization experiments have been performed which show first-order behavior. The end-group was proven by NMR spectroscopy.
Datum: 16.08.2016


A Mixed Porphyrin–Schiff Base Dysprosium(III) Single-Molecule Magnet

The mixed porphyrin–Schiff base potassium dysprosium(III) complex [K(TBPP)Dy(L)(CH3CN)2] [H2TBPP = 5,10,15,20-tetrakis(4-tert-butylphenyl)porphyrin; H2L = N,N′-bis(3-methoxysalicylidene)benzene-1,2-diamine; 1] was isolated from the reaction between the metal-free Schiff base ligand H2L and the half-sandwich porphyrinato dysprosium compound [Dy(TBPP)(acac)] (Hacac = acetylacetone) in the presence of KOH. A sandwich-type double-decker structure has been unambiguously revealed by single-crystal X-ray diffraction analysis. Static and dynamic magnetic measurements disclosed the slow relaxation behavior of this new double-decker compound and indicated its single-molecule magnet (SMM) nature. Comparative studies on the magnetic properties of 1, the homoleptic bis[5,10,15,20-tetrakis(4-tert-butylphenyl)porphyrinato]dysprosium double-decker [DyH(TBPP)2] (2), and the bis(Schiff base)dysprosium double-decker {[Dy[Zn(L)Cl]2(DMF)2]·Cl} (3, DMF = N,N-dimethylformamide) indicate the effect of the ligand field (LF), through the deviation of the dysprosium coordination geometry from the ideal D4d form, on the SMM properties of 1–3 in addition to the effect of the charge distribution over the DyIII ion.A mixed porphyrinato–Schiff base potassium dysprosium(III) double-decker single-molecule magnet is synthesized and structurally characterized for the first time.
Datum: 16.08.2016


PhP=CPh2 and Related Phosphaalkenes: A Solution Equilibrium between a Phosphaalkene and a 1,2-Diphosphetane

The synthesis of phosphaalkenes, ArP=C(R)Ph (1, a: Ar = Ph, R = Ph; b: Ar = o-Tol, R = Ph; c: Ar = Mes, R = H), bearing sterically less hindered substituents is reported. Phosphaalkenes 1a–b were prepared by treating Ph2C=O with ArP(Li)SiMe3, whereas 1c was accessed from the AlCl3-mediated reaction of ArP(SiMe3)2 and PhC(O)H. Both 1a and 1b dimerize to afford their respective 1,2-diphosphetanes (2a and 2b). Compound 2a was characterized by X-ray crystallography. Dissolution of pure 2a in THF resulted in a temperature dependent equilibrium with monomer 1a (ΔHo = –94.6 ± 14.6 kJ mol–1; ΔSo = –284 ± 48 J mol–1 K–1). Although monomer E/Z-1c was identified in solution by its characteristic downfield 31P NMR chemical shift (δ = 247.1, 231.5), it was accompanied by the formation of what we believe are oligomers (δ = –25 to 10 ppm, br.). Attempts to trap phosphaalkenes 1a and 1b by treatment with W(CO)5(MeCN) afforded mixtures of complexes W(CO)5(1a–b) (4a–b) and W(CO)4(1a–b)2 (5a–b), the disubstituted species being subjected to X-ray crystallographic characterization (5a).The isolable 1,2-diphosphetane [PhPCPh2]2 serves as a precursor to phosphaalkene PhP=CPh2 in solution. This, and related phosphaalkenes may be isolated as tungsten(0) complexes.
Datum: 16.08.2016


σ-Bond Activation in Aluminium-Functionalized Alkynylchlorogermanes: Facile Insertion of Isocyanate and Azide into Al–C and Ge–Cl Bonds

Hydroalumination of Cl-functionalized alkynylgermanes yielded mixed Al/Ge compounds (1). The Cl atoms adopted bridging positions between the Ge and Al atoms to form four-membered GeCAlCl heterocycles with relatively long endocyclic Ge–Cl and Al–C bonds. Reactions with isocyanates resulted in the insertion of the heterocumulenes into both activated bonds and the formation of four-membered GeC2N heterocycles, which featured exocyclic C–C and C–O double bonds with C–O oxygen atoms coordinated to ClAltBu2 molcules (2). An intermediate (3) was isolated with Ad-NCO (Ad = 1-adamantyl) from the insertion of isocyanate into the endocyclic Al–C bond. These products are characterized by intact Ge–Cl bonds and a chelating coordination of the Al atoms by the OCN groups. They rearranged at elevated temperature to yield compounds of type 2. Quantum-chemical calculations were applied to evaluate the thermodynamics of these isocyanate insertion reactions. An azide reacted similarly by insertion into the Al–C and Ge–Cl bonds and afforded a GeCN3 heterocycle with an intact N3 group.σ-Bond activation results from an intramolecular interaction between Al and Cl atoms in dialkylaluminum-functionalized chlorogermanes. The concomitant weakening of the Ge–Cl and Al–C(vinyl) bonds facilitates insertion reactions with isocyanate and azide and the formation of unusual structural motifs by C–C and C–N bond formation.
Datum: 16.08.2016


A {Cu4I4} Cluster Supported on a Metal-Dithiolato Complex Anion Causes its Conformational Change Leading to a Doubly-Bridged Curved Coordination Polymer and its Reactivity with a Diamine Resulting in the Emergence of a [M(diamine)(dithiolate)] System

When dithiolene-based coordination complexes [Bu4N]2[MII(tdas)2] (tdas2– = 1,2,5-thiadiazole-3,4-dithiolate; M = Ni, Pd, Pt) are reacted separately with CuI, it results in the formation of chain-like coordination polymers [Bu4N]2n[MII(tdas)2Cu4I4]n [M = Ni (compound 1), Pd (compound 2), Pt (compound 3)] in which each metal(bis)dithiolato complex unit supports a {CuI4I4} cluster unit. Two of the crystal structures and powder X-ray diffraction studies confirm that compounds 1, 2 and 3 are isomorphous with each other showing the abundance of a doubly-bridged “curved” chain-like structure formed by the coordination of two “N” donor atoms of each [MII(tdas)2]2– complex unit to two Cu+ ions of two adjacent {CuI4I4} cluster units and by the coordination of two Cu+ ions of a {CuI4I4} cluster with its neighbouring two [MII(tdas)2]2– complex anions through their “N” donor atoms from opposite sides. Since the [MII(tdas)2]2– complex anion generally has a planar geometry, which becomes bent upon supporting a {CuI4I4} cluster in the present study, the Cu–S interaction in [MII(tdas)2Cu4I4]2– is responsible for the bending conformation of the metal–dithiolato complex unit. This bending structure of the complex anion [MII(tdas)2]2– in [MII(tdas)2Cu4I4]2– describes a situation where the central part of the complex anion is pulled away towards the {CuI4I4} cluster through Cu–S bonds. This causes a “curve-like” structure throughout the resulting doubly-bridged chain in compounds 1, 2 and 3. The second important aspect of the present work is an interesting reactivity of this doubly-bridged coordination polymer with a bidentate chelating ligand, tetramethylethylenediamine (TMEDA). Compound [Bu4N]2n[NiII(tdas)2Cu4I4]n (1), a representative member of the series of compounds 1–3, was treated with TMEDA, which resulted in a square planar complex [Ni(tdas)(TMEDA)] (4) belonging to a mononuclear [MII(N2S2)]-type system (where N2 = bidentate N∩N donor ligand, mostly a bipyridine type, and S2 = dithiolato ligand) representing an important class of compounds for photophysical properties. Compound 4 exhibits emission at room temperature in the visible region.A dithiolene-based coordination complex, on treatment with CuI, results in the formation of a coordination polymer in which each metal(bis)dithiolene complex unit, undergoing a conformational change, supports a {CuI4I4} cluster unit.
Datum: 16.08.2016


Amidinium-Containing 2D [MnCr] Dimetallic Oxalate-Based Networks – The Influence on Structure and Magnetism Explored by Combining Experience and Theory

Three X2+ bisamidinium dications are inserted into oxalate-based dimetallic [MnCr] compounds of formula X[MnII(CH3OH)CrIII(ox)3]2·nS [X2+ = C14N4H202+ (cation A2+, compound 1), C14O2N4H202+ (cation B2+, compound 2), C16N4H242+ (cation C2+, compound 3); n = 4 (1–2), 2 (3); S = CH3OH (1–2), CH3CN (3); ox = oxalate]. Single-crystal X-ray analysis of 1–3 reveals that Mn–Cr oxalate-bridged dimetallic coordination networks form corrugated two-dimensional (2D) layers based on heptacoordinate MnII ions surrounded by six oxygen atoms from three bis-bidentate oxalate ions and one oxygen atom from a coordinated methanol molecule. In 1–3, the observed coordination environments of the MnII ions are close to capped trigonal prismatic (CTPR-7) according to continuous shape measurements (CSM). Curie–Weiss temperatures of 0.62, 0.42, and 0.54 K for 1–3, respectively, were deduced from the magnetic susceptibility measurements and reveal dominant ferromagnetic exchange interactions. Ab initio calculations up to the DDCI-2 level were performed on [MnCr] dimeric units and allowed the evaluation of the exchange interactions in 1–3. Three oxalate-based dimetallic [MnCr] compounds with intercalated bisamidinium dications are studied, and magnetostructural correlations are provided.
Datum: 16.08.2016


3,5-Dimethylpyrazolyl-Substituted Di- and Trisiloxanes

The synthesis and characterization of di- and trisiloxanes with 3,5-dimethylpyrazolyl (pz*) moieties are presented. Disiloxanes of the type O(SiMe3–npz*n)2 (n = 1, 2, and 3 in 2, 3, and 4, respectively) are easily accessible through a trans-silylation approach. Crystal structure analyses of compound 4 and the two side products 5 and 6 illustrate different coordination motifs of pz* (terminal vs. bridging) in the disiloxane system. The reaction of O2Si3Cl8 with Me3Sipz* led to the unsymmetrically substituted trisiloxane pz*3SiO-Sipz*2O-SiCl2pz* (7) with bridging pz* units and tetra- and pentacoordinate silicon atoms and the fully pyrazolyl-substituted trisiloxane O2Si3pz*8 (8), depending on the choice of the reaction conditions. The 29Si NMR properties of 7 were investigated by 29Si CP/MAS NMR spectroscopy and supporting quantum chemical calculations analyzing the principal components of the chemical-shift tensor for all three silicon atoms in this molecule. The reaction of 3,5-dimethypyrazolyltrimethylsilane with chloro-substituted disiloxanes and octachlorotrisiloxane afforded fully substituted disiloxanes and trisiloxanes. The properties of a special asymmetric trisiloxane (see picture) were investigated with respect to its formation and 29Si NMR shielding-tensor components.
Datum: 16.08.2016


Snap-Shots of a Reduction Pathway: The Reaction of WCl6 with Copper Powder

A combined differential scanning calorimetry (DSC)/X-ray diffraction (XRD) methodology is used to search and identify compounds in the Cu/W/Cl system based on the successive reaction of WCl6 with copper powder. Thermal effects monitored by DSC are used to detect reaction pathways and phase formations of compounds. A series of five new and one already known compounds is discovered as crystalline phases in the Cu/W/Cl system and structurally characterized by XRD. The reaction of WCl6 with elemental copper begins at temperatures as low as 60 °C with the formation of crystalline powders of α-CuxWCl6. Continuing reaction stages include the successive formation of crystalline phases β-CuxWCl6, γ-CuxWCl6, α-Cu2W2Cl10, β-Cu2W2Cl10, and Cu2[W6Cl14].A combined differential scanning calorimetry (DSC)/X-ray diffraction (XRD) methodology is used to investigate the successive reduction of WCl6 with copper powder. This approach shows the reductive intercalation of copper ions to yield α-CuxWCl6, β-CuxWCl6, γ-CuxWCl6, α-Cu2W2Cl10, β-Cu2W2Cl10, and Cu2W6Cl14.
Datum: 16.08.2016


The Role of Bulkiness in Haptotropic Shifts of Metal–Cumulene Complexes

In metal–cumulene complexes, the metal easily slides through the double bonds of the chain. A series of late-transition-metal–[5]cumulene complexes has been studied by theoretical and experimental methods in order to understand the factors that control such haptotropic shifts. The bulkiness of the cumulene terminal groups plays a central role in the tautomeric preferences. The quantum theory of atoms in molecules and the electron localizability indicator show that the M–C bond closer to the terminal groups is significantly weakened by steric interactions between these groups and the rest of ligands around the metal center. The results emphasize that special attention should be paid to the orientation of both the bulky substituents at the cumulene and other voluminous ligands around the metal, because the orientation of such moieties is important in predicting the direction of the haptotropic equilibrium correctly.To correctly predict the direction of haptotropic shifts in metal–cumulene complexes, not only is the bulkiness of terminal groups important, but also the orientation of these groups with respect to the remaining ligands around the metal center.
Datum: 16.08.2016


Molecular and Nanoaggregation in Cyclometalated Iridium(III) Complexes through Structural Modification

New terpyridyl ligands TP1, TP2 and cyclometalated iridium(III) complexes 1 and 2 based on these ligands have been synthesized. The ligands and complexes have been characterized by elemental analysis and spectroscopic studies (ESI-MS, 1H and 13C NMR, UV/Vis, fluorescence). The molecular structure of 1 has been verified by X-ray single-crystal analysis. It has been unambiguously established that variation of the substituents on 1 and 2 leads to molecular aggregation in 1, while 2 remains nonaggregated. Furthermore, complexes 1 and 2 have been successfully utilized as capping agents for the stabilization of gold nanoparticles (AuNPs). It is of note that 1 forms discretely, while 2 aggregates AuNPs through the assemblage of ultrasmall nanoparticles. It has been affirmed by 1H NMR titration studies that –NH groups from 1 and 2 are involved in the capping of AuNPs. The role of simple structural variations in directing molecular and nanoaggregation has been clearly established for the first time by spectroscopic (UV/Vis, fluorescence, 1H NMR titration) and morphological studies [SEM, TEM, EDX (energy-dispersive X-ray), DLS (dynamic light scattering)]. The role of simple structural variations in directing molecular and nanoaggregation has been established for the first time in two new cyclometalated iridium(III) complexes with the help of various spectroscopic (UV/Vis, fluorescence, 1H NMR titration) and morphological analyses [SEM, TEM, EDX (energy-dispersive X-ray), DLS (dynamic light scattering)].
Datum: 16.08.2016


Neutral and Cationic Palladium Complexes of P-Stereogenic Phosphanes Bearing a Heterocyclic Substituent

The coordination chemistry of 13 optically pure P-stereogenic diarylmonophosphanes P(Het)PhR [Het = 4-dibenzofuranyl (DBF), 4-dibenzothiophenyl (DBT), 4-dibenzothiophenyl S,S-dioxide (DBTO2) and 1-thianthrenyl (TA); R = OMe, Me, iPr, Fc (ferrocenyl)] to Pd-allyl moieties is described. Both neutral [PdCl(η3-(2-methylallyl)(κP-P)] and cationic [Pd{η3-(2-methylallyl)(κP-P)2}]PF6 complexes have been prepared. Coordination of the heteroatom of the heterocycle was only possible in the case of TA-based phosphanes; these furnished complexes of the type [Pd{η3-(2-methylallyl)(κ2P,S-P)}]PF6 after chloride abstraction with TlPF6. The crystal structure of the complex [Pd(η3-2-methylallyl)(κ2P,S-PPh(OMe)(1-TA)]PF6 is reported. The neutral Pd complexes were found to be highly active in the hydrovinylation of styrene after activation with AgBF4, except for the TA-based phosphanes. The cationic Pd complexes were evaluated in allylic alkylation and amination with the model substrate rac-trans-1,3-diphenylprop-2-enyl acetate (rac-I), achieving total conversions and up to 70 % ee.The coordination chemistry of a series of P-stereogenic monophosphorus ligands, containing a heterocyclic substituent, towards the Pd-methallyl moiety has been studied. Some of the obtained complexes are very active in catalytic hydrovinylation whereas full conversion and a 70 % ee have been achieved in asymmetric allylic substitution.
Datum: 16.08.2016


Five Disk-Shaped {MII7} (M = Mn, Fe, Co, Cu, Zn) Clusters and One Capsule-Like {CuII6NaI2} Cluster Assembled from the Same Schiff Base Ligand

Six transition-metal clusters of compositions [Mn7L6](NO3)2·2CH3OH (1), [Fe7L6](NO3)2·2CH3OH (2), [Co7L6](NO3)2·2CH3OH (3), [Cu7L6](NO3)2 (4), [Zn7L6](NO3)2·2CH3OH (5), and [Cu6Na2L6](NO3)2·4CH3OH (6) {H2L = 2-(2-hydroxy-3-methoxybenzylideneamino)phenol} have been synthesized under solvothermal conditions. The structures of 1–6 have been established based on single-crystal X-ray diffraction studies. Complexes 1–5 possess disk-shaped {MII7} cores, with the central MII ion and the six peripheral MII ions being linked by six µ3-O atoms. The six MII ions of the rim of the disk are bridged in a pairwise manner by six µ2-O atoms. Complex 2 is a very rare example of a disk-shaped {Fe7} cluster in which all of the Fe atoms exhibit +2 oxidation state. Furthermore, this is the first time that the five isostructural heptanuclear clusters were constructed by using an identical Schiff base ligand. The molecule of complex 6 contains a capsule-like {Cu6Na2} core. In this core, two sodium ions reside on the two vertices of the capsule and the 12 vertices of the {Cu6O6} hexagonal prism are occupied by alternately arrayed six CuII ions and six O atoms. Photoluminescence studies suggest strong emission for 5 in the solid state at room temperature. Variable-temperature dc magnetic susceptibility studies were carried out on polycrystalline samples of 1–4 and 6. The ac susceptibility studies were also performed with 3. Strong out-of-phase, χ′′, signals were observed for 3 at zero field, suggesting that 3 is a class of single molecule magnet (SMM).Five transition-metal {MII7} clusters and one capsule-like {Cu6Na2} compound have been synthesized by employing an identical Schiff base ligand. Complex {CoII7} exhibits single molecule magnetic behavior.
Datum: 19.07.2016






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