Crystallization of cesium complex containing bis(2-propyloxy)calix[4]crown-6 and bis[(trifluoromethyl)sulfonyl]imide

Publication year: 2012
Source:Inorganica Chimica Acta, Volume 390

Taoxiang Sun, Zheming Wang, Xinghai Shen

A complex of Cs⁺ with the calixcrown bis(2-propyloxy)calix[4]crown-6 (BPC6) and bis[(trifluoromethyl)sulfonyl]imide (NTf2 ^?), an anion of ionic liquid (IL), was crystallized in the interface region between n-octanol and water. The compound was characterized by single crystal X-ray diffraction, ESI-MS, FT-IR, TGA and PXRD. Cs⁺ is coordinated with BPC6 by both the six oxygen atoms of the crown and the cation–? interactions, and with the anion NTf2 ^? via one oxygen atom of the sulfonyl group. This single crystal explains the good extraction ability of BPC6 to Cs⁺ and reflects a coordinating interaction of NTf2 ^? with the deficient complex [Cs·BPC6]⁺ during the extraction with an IL as diluent.

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Posted on 28 May 2012 | 12:58 pm

Prelim v-xi contents (synopsis and pictogram)

Publication year: 2012
Source:Inorganica Chimica Acta, Volume 389

Posted on 28 May 2012 | 12:58 pm

Amino-acid based coordination polymers

Publication year: 2012
Source:Inorganica Chimica Acta, Volume 389

Jana K. Maclaren, Christoph Janiak

Five new transition metal–amino acid coordination polymers, including two copper compounds 1D-{Cu(d-?-PhGly)2} (1), 1D-{Cu(l-Trp)2} (2) and three cadmium compounds 2D-{Cd(d-Leu)2} (3) 2D-{Cd(d-Phe)2} (4) and 2D-{[Cd(d-Phe)(4,4?-bipy)H2O][NO3]} (5) are structurally characterized (PhGly=phenylglycinato, Trp=tryptophanato, Leu=leucinato, Phe=phenylalaninato in enantiopure form, 4,4?-bipy=4,4?-bipyridine). Single crystals were obtained by slow diffusion of the metal salt and the ligand in a water–methanol mixture. The enantiopure amino acetate ligands led to homochiral crystallization of 1–5 in the non-centrosymmetric space group P21. Characterization by single-crystal X-ray diffraction, infrared and Raman spectroscopy showed that the copper compounds 1 and 2 form twofold helices around the 21 screw axis and the cadmium compounds 3–5 yield two-dimensional coordinative layers also with twofold helices around the 21 axes for 3 and 4. The Cu-amino-acetate/carboxlyate helices are connected by N–H···O hydrogen bonds and very long Cu?O–carboxylate contacts to supramolecular 2D layers. Crystal packings of 2D layer structures in 1–4 show a separation of the hydrophobic alkyl groups from the hydrophilic M-amino-carboxylate region. Charge-assisted Cu⁽⁺⁾?^(?)O interactions and N–H···^(?)O hydrogen-bonding interactions in the hydrophilic region are the driving force of “hydrophobic exterior layer” formation with a hydrophilic interior exposing the hydrophobic alkyl groups to the exterior. Stacking of the layers occurs through weak van der Waals interactions between the alkyl groups. This correlates with the crystal morphology, with formation of thin crystal plates along the stacking direction. In 5 the Cd-?-amino carboxylate-?N,O:O? units with a pentagonal–bipyramidal Cd atom form strands, and these strands are then joined through the rigid 4,4?-bipy linkers to a coordinative 2D layer. The nitrate anions connect these layers with charge-assisted (aqua)O–H···^(?)O(nitrate) and (amino)N–H···^(?)O(nitrate) hydrogen bonds to a supramolecular 3D network.

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Posted on 28 May 2012 | 12:58 pm

Chalcogen–chalcogen interactions in trichalcogenaferrocenophanes. Crystal structure of 2-selena-1,3-ditellura[3]ferrocenophane [Fe(C5H4Te)2Se]

Publication year: 2012
Source:Inorganica Chimica Acta, Volume 390

Minna M. Karjalainen, Raija Oilunkaniemi, Risto S. Laitinen

The preparation, ⁷⁷Se and ¹²⁵Te NMR spectroscopic characterization, and crystal structure of 2-selena-1,3-ditellura[3]ferrocenophane [Fe(C5H4Te)2Se] have been reported. The complex crystallizes in a triclinic crystal system with the space group $P\overline{1}$. The comparison of the X-ray structure of [Fe(C5H4Te)2Se] with those of other members in the [Fe(C5H4E)2E?] (E, E?=S, Se, Te) series shows that the intermolecular chalcogen–chalcogen interactions are weak in case of sulfur or selenium, but become significant for interactions involving tellurium. This is consistent with the concept of secondary bonding interactions between the atoms of heavy main group elements.

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Posted on 28 May 2012 | 12:58 pm

Two zinc(II) and cadmium(II) complexes based on the V-shaped ligand 2,6-bis(2-benzimidazolyl)pyridine: Synthesis, crystal structure, DNA-binding properties and antioxidant activities

Publication year: 2012
Source:Inorganica Chimica Acta, Volume 390

Hui-Lu Wu, Jing-Kun Yuan, Xing-Cai Huang, Fan Kou, Bin Liu, Fei Jia, Kai-Tong Wang, Ying Bai

Two zinc(II) and cadmium(II) complexes based on a V-shaped ligand 2,6-bis(2-benzimidazolyl)pyridine (bbp) have been synthesized and characterized by elemental analysis, molar conductivities, IR, UV–Vis spectra and X-ray single crystal diffraction. Zn(II) and Cd(II) ions are six-coordinated in the structures of [Zn(bbp)2](pic)2·2DMF (1) and [Cd(bbp)2](pic)2·2DMF (2) (pic=picrate), and forming a distorted octahedron. The DNA-binding properties of the complexes were investigated by spectrophotometric methods and viscosity measurements. The experimental results suggest the complexes bind to DNA in an intercalation mode, and DNA-binding affinity of the Zn(II) complex is stronger than that of the Cd(II) complex owning to the different V-shaped angle (?V). Antioxidant assay in vitro shows that both two complexes possess significant hydroxyl radical scavenging activity, and the Zn(II) complex also reveal potent superoxide radical scavenging activity.

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Posted on 28 May 2012 | 12:58 pm

Construction and property investigation of inorganic–organic hybrid materials based on metal–salens and Keggin polyoxometalates

Publication year: 2012
Source:Inorganica Chimica Acta, Volume 390

Xing Meng, Hai-Ning Wang, Xin-Long Wang, Guang-Sheng Yang, Shuang Wang, Kui-Zhan Shao, Zhong-Min Su

Four hybrid materials based on the Keggin polyanions and metal–salens, namely, [Mn(salen)(CH3OH)2]4[SiW12O40] (1), [Mn(salen)(H2O)]2[Mn(salen)(H2O)][PW12O40] (2), [NH(CH2CH3)3]2[Mn(salen)(CH3OH)]2[SiW12O40]·2CH3OH (3), and [(Cu(salen))2Cu(H2O)]2[SiW12O40] (4) (H2salen=N,N?-ethylenebis(salicylideneimine)) have been successfully synthesized. All the compounds are characterized by X-ray single-crystal diffractions, elemental analyses, IR spectra, and thermogravimetric analyses (TGA). Crystal structure analysis reveals that compound 1 exhibits a supramolecular structure containing one Keggin-type [SiW12O40]^4? heteropolyanion and four Mn^III–salen units. In compound 2, the [PW12O40]^3? polyoxoanions and Mn^III–salen complex cations are regularly arranged along the c-axis showing an alternating packing arrangement of anionic and cationic layers. While in compound 3, the polyoxoanion [SiW12O40]^4? is covalently decorated by two [Mn(salen)(CH3OH)]⁺ fragments via two terminal oxygen atoms in the opposite sites, giving birth to an unusual Keggin anion supporting transition metal–salen complexes. Compound 4 represents the first example that POM supports trinuclear copper–salen complexes. Photocatalytic experiments of 1–4 indicate that they possess high catalytic activity for photodegradation of RhB under UV irradiation. In addition, the electrochemical behaviors of 1 and 2 are well investigated.

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Posted on 28 May 2012 | 12:58 pm

A Mn(III) chain derived from Mn12–acetate that exhibits both glauber dynamics and antiferromangetic ordering regimes

Publication year: 2012
Source:Inorganica Chimica Acta, Volume 389

Andrey V. Prosvirin, Hanhua Zhao, Kim R. Dunbar

In this work, we present a detailed AC magnetic susceptibility investigation of the metamagnet {[Mn(OH)(CH3CO2)2]·CH3CO2H·H2O}? (1). Compound 1 was previously reported and the magnetic properties were investigated. The data revealed that the compound is a linear-chain antiferromagnet with a phase transition at TN =6.1K to an ordered antiferromagnetic state and a metamagnetic transition at approximately 1000Oe from the antiferromagnetic phase to a paramagnetic phase. In this new study we report detailed AC susceptibility measurements which reveal frequency dependent data indicative of a slow relaxation process which was not previously described. These additional magnetic data support the conclusion that this compound is a rare example of an antiferromagnetic ordered system that displays magnetic relaxation properties induced by the intrinsic single chain magnet (SCM) properties of the canted homospin chains composing the material.

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Posted on 28 May 2012 | 12:58 pm

Molecular complex from two different binuclear copper 1,4,5,8-naphthalenetetracarboxylate complexes

Publication year: 2012
Source:Inorganica Chimica Acta, Volume 390

Devendra Singh, Jubaraj B. Baruah

Two different binuclear copper complexes [Cu2(Phen)4(NTC)] (A) and [Cu2(Phen)2(NTC)(H2O)4] (B) form a stable molecular complex having a composition [Cu4(Phen)6(NTC)2(H2O)4·22H2O] (1) (where Phen=1,10 phenanthroline and H4NTC=1,4,5,8-naphthalenetetracarboxylic acid). Different ?-interactions as well as intermolecular hydrogen bonding interactions between the two complexes A and B result in the formation of 3D channel like structures of approximate 18×14Å dimension are filled by lattice water molecules. Moreover, 3D network of complex A itself makes the required space in the crystal lattice to accommodate 1D zigzag chains of complex B.

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Posted on 28 May 2012 | 12:58 pm

Synthesis, characterization and X-ray studies of new six–seven membered rings [4.5.0] heterobicyclic system of monomeric boronates

Publication year: 2012
Source:Inorganica Chimica Acta, Volume 390

José María Rivera, Enrique Méndez, Raúl Colorado-Peralta, Susana Rincón, Norberto Farfán, Rosa Santillán

Different tridentate ligands derived from ethanolamines and 2-hydroxyacetophenone, 2-hydroxybenzophenone and salicylaldehyde were reacted with two equivalents of phenylboronic acid to obtain compounds 6a – 6f which are [4.5.0] heterobicyclic systems with a B?O?B structural unit. The boronates were fully characterized and two heterobicyclic [4.5.0] structures have been analyzed by X-ray crystallography, where a series of parameters such as bond distances, bond angles, torsion angles, tetrahedral character at the boron atom and deviation of the boron atom from the mean plane have been evaluated.

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Posted on 28 May 2012 | 12:58 pm

Copper(II) complexes of aliphatic tridentate amine/dithioether ligands – Synthesis and molecular structures

Publication year: 2012
Source:Inorganica Chimica Acta, Volume 390

Marc Blomenkemper, Henning Schröder, Tania Pape, F. Ekkehardt Hahn

Three new tridentate ligands (1–3) featuring a central secondary amine linked by ethylene bridges to two thioether donor functions with S-methyl or S-benzyl substituents have been synthesized and reacted with copper(II) chloride or copper(II) nitrate. The resulting complexes of type [CuX2(L)] (L=amine-dithioether ligand) 6, 7, and 9 exhibit a square-pyramidal coordination geometry with the nitrogen and sulfur donor groups of the tridentate ligand occupying three of the basal binding sites at the metal ion. Two chloro (6 and 7) or a nitrato ligand (9) originating from the metal precursor salt complete the coordination sphere of the copper(II) ion. The apical donors are bonded with significantly longer bond distances compared to identical donors in the basal plane. The weakly bound apical chloro ligand of 6 can be abstracted with silver(I) nitrate effecting the formation of the dinuclear complex 10 featuring a nitrato ligand coordinated to two copper(II) centers in a bridging fashion. For all copper(II) complexes the observed Cu–S bond distances are very similar and not significantly influenced by alteration of the alkyl group at the thioether donor function.

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Posted on 28 May 2012 | 12:58 pm

Anion sensing by rhenium(I) carbonyls with polarized N–H recognition motifs

Publication year: 2012
Source:Inorganica Chimica Acta, Volume 389

Kai-Chi Chang, Shih-Sheng Sun, Alistair J. Lees

This article describes our recent research results on several rhenium(I) carbonyls complexes with polarized N–H recognition motifs as anion receptors. Structurally simple and easily synthesized luminescent anion receptors containing an amide-type anion binding site and a rhenium(I) tricarbonyl pyridine signaling unit have been developed, and they display outstanding sensitivity and selectivity toward a variety of anionic species. Moreover, thioamides and thiourea derivatives of 2,6-pyridinedicarbonyl dichloride, isophthaloyl dichloride and terephthaloyl dichloride have been synthesized. These ligands have been incorporated in dinuclear rhenium(I) diimine tricarbonyl complexes and provide anion recognition properties in these complexes. Furthermore, the related rhenium(I) complex featuring sulfonamide interacting sites that incorporate the highly chromophoric ?-conjugated quinoxaline moiety has been prepared, characterized, and its photophysical properties were also studied.

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Posted on 28 May 2012 | 12:58 pm

In situ surface functionalization of magnetic nanoparticles with hydrophilic natural amino acids

Publication year: 2012
Source:Inorganica Chimica Acta, Volume 389

Haiou Qu, Hui Ma, Weilie Zhou, Charles J. O’Connor

The surface of magnetic iron oxide nanoparticles has been modified with hydrophilic natural amino acids via an in situ method. A rapid ligand exchange reaction was induced at elevated temperatures to replace the original labile solvent layer with amino acids. The functionalized nanoparticles were quasi-spherical and well separated with an average diameter around 7nm. The resulted products were examined to be highly crystalline and phase-pure Fe3O4. The present of amino acids on the surface of the nanoparticles was verified by Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy, which indicated successful ligand exchange. Zeta potential and dynamic light scattering measurement suggested that functionalized magnetic nanoparticles were well dispersed in both basic and acidic aqueous solution with small polydispersity. The uncoordinated amine groups are highly reactive and available for either conjugation with biocompatible polymers or attachment of small gold nanocrystals, so as to prepare dual-functional nanocomposite.

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Posted on 28 May 2012 | 12:58 pm

Dinuclear iridium complexes with unsupported Ir–Cl–Ir bridges

Publication year: 2012
Source:Inorganica Chimica Acta, Volume 390

Joseph S. Merola, Trang Le Husebo, Henry E. Selnau

Two unusual dinuclear iridium complexes are reported with unsupported bridging chloride ligands. The first comes from an aqueous solution of H2ClIr(PMe3)3 by the addition of KPF6. The second is formed in the reaction between H(C6H5)ClIr(PMe3)3 and TlPF6 in dichloromethane. Single crystal X-ray structures are provided for both ?-chlorodiiridium complexes.

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Posted on 28 May 2012 | 12:58 pm

Direct assembly of a metallodendrimer encompassing seven triruthenium clusters units

Publication year: 2012
Source:Inorganica Chimica Acta, Volume 390

Sergio H. Toma, Jonnatan J. Santos, Sofia Nikolaou, Koiti Araki, Henrique E. Toma

A general strategy for the assembly of dendrimeric metallo-cluster species based on tritopic trinuclear ruthenium acetate complexes is demonstrated. First, a central core consisting of a [Ru3O(CH3COO)6(TPEB)3]PF6 complex (G0), where TPEB is the tripodal 1,3,5-tri-4-pyridyl-1,2-ethenylbenzene ligand, was synthesized and then reacted with the end-capping complex [Ru3O(CH3COO)6(py)2(MeOH)]PF6, thus composing the first generation shell of a dendrimer encompassing twenty-one ruthenium ions (G1). The core and dendrimeric complexes were characterized by elemental analysis, UV–Vis, ¹H NMR, ESI-MS spectrometry and Differential pulse voltammetry. All results were consistent with the structure of that multinuclear cationic dendrimeric species. The isotopologic profile of daughter fragments and the strength of the metal–ligand bonds were carefully investigated providing the fragmentation pathway for the metallo-dendrimer upon ESI-MS dissociation conditions.

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Posted on 28 May 2012 | 12:58 pm

Novel building units in the construction of materials of the oxomolybdate–organodiphosphonate/copper(II)–dipodal-organonitrogen ligand system: Structural influences of dipodal ligand tether length and flexibility

Publication year: 2012
Source:Inorganica Chimica Acta, Volume 389

Mark Bartholomä, Hoi Chueng, Steven Pellizzeri, Kenneth Ellis-Guardiola, Stephanie Jones, Jon Zubieta

The hydrothermal reactions of copper(II) acetate, MoO3, 1,4-butylenediphosphonic acid and a ligand of the N,N,N?,N?-tetrakis(pyridine-2-ylmethyl)alkyl-?,?-diamine (Ln, where n is the number of methylene groups) in the presence of HF provided crystals of [{Cu2(L7)(H2O)2}Mo5O15{O3P(CH2)4PO3}]·2H2O (1·2H2O) and [{Cu2(L5)}Mo6O18(H2O){O3P(CH2)4PO3}]·14H2O (2·14H2O). Compound 1 contains the common pentanuclear cluster building block {Mo5O15(O3PR)2}^4?, extending into one-dimensional chains through the alkyl tethers of the diphosphonate ligand. Each pentanuclear subunit bonds to four copper(II) sites of the {Cu2(L7)(H2O2)}⁴⁺ subunits that serve to link each chain to five adjacent chains to propagate the structure in three dimensions. The Cu/Mo/P/O inorganic substructure which arises from this juxtaposition of building motifs is a one-dimensional {Cu2Mo5O15(O3P?)2} unit consisting of clusters linked through Cu(II) sites. The alkyl arms of the diphosphonate and nitrogen ligands radiate outward to link to adjacent chains and propagate the structure in three-dimensions. In contrast, compound 2 exhibits a hexanuclear building unit {Mo6O18(H2O)(O3P?)2}^4?, which again extends into a chain through the tethering diphosphonate ligands. Each cluster bonds to four Cu(II) centers to generate one-dimensional inorganic substructures of the type {Cu2Mo6O18(H2O)(O3P?)2} n . In contrast to 1, the {Cu2(L5)}⁴⁺ subunits of 2 associate with a single chain, rather than radiating outward to link to adjacent chains. Consequently, the three-dimensional expansion is effected through the diphosphonate tethers.

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Posted on 28 May 2012 | 12:58 pm

High-yield postsynthetic modification of MOF with organic–metal precursors

Publication year: 2012
Source:Inorganica Chimica Acta, Volume 390

Jongsik Kim, Dong Ok Kim, Dong Wook Kim, Jeasung Park, Mi Sun Jung

The specific yield of postsynthetic modification for modified IRMOF-16 (HCC-1), synthesized using 1,4-di(4-carboxy-2-hydroxyphenyl)benzene as organic ligand and Zn(NO3)2·6H2O as metal source, respectively, has been investigated with the variation of its BET surface area, reaction time and organic–metal precursor. Two kinds of HCC-1 having different values of BET surface area (HCC-1H: 3000m²/g and HCC-1L: 2000m²/g) were prepared via solvothermal method for the study of effect of BET surface area, whereas isopropoxytitanatrane and tetrabenzyl titanium were adopted as organic–metal precursors It was observed that even if the specific yields of postsynthetic modification for both organic–metal precursors increased with the value of BET surface area of HCC-1, isopropoxytitanatrane showed relatively higher values than those of tetrabenzyl titanium during the entire range of reaction. These observations led us to conclude that HCC-1H has higher specific number of –OH groups, active sites for postsynthetic modification, and tetrabenzyl titanium experiences more difficulty in diffusing deep into HCC-1 due to its relatively larger molecular size. For the effect of reaction time, while it increased slowly with the reaction time until 48h and then leveled off for HCC-1H, it increased during the entire range of reaction time for HCC-1L.

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Posted on 28 May 2012 | 12:58 pm

Oxidation states and redox behavior of ruthenium ammine complexes with redox-active dioxolene ligands

Publication year: 2012
Source:Inorganica Chimica Acta, Volume 390

Isao Ando, Takemasa Fukuishi, Kikujiro Ujimoto, Hirondo Kurihara

Synthesis of ruthenium-dioxolene complexes with ammines [Ru(NH3)4(diox-R)] ^{n +}, where diox-R is a dioxolene with substituent R=3,5-di-tert-butyl, H, tetrachloro, and 4-nitro, was carried out. These complexes were characterized by spectroscopy, magnetic susceptibility measurements, and cyclic voltammetry. The oxidation states of ruthenium and the redox-active dioxolene ligand in the complexes varied depending on the nature of the dioxolene substituents. [Ru(NH3)4(diox-R)] ^{n +} (R=3,5-di-tert-butyl and H) has a divalent ruthenium and dioxolene in the quinone oxidation state with a minor amount of the complex in Ru(III)-semiquinonato oxidation state. The complexes exhibited valence tautomerism depending on the donor number of solvents. However, [Ru(NH3)4(diox-R)] ^{n +} (R=tetrachloro and 4-nitro) has a trivalent ruthenium and dioxolene in the catecholate oxidation state. Electrochemical and spectroelectrochemical investigation of these complexes revealed that their electrochemical behavior depended on not only the oxidation state of the prepared complex but also the nature of the dioxolene substituent in the complex. Their redox reaction was found to proceed by the EC mechanism involving valence tautomerism.

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Posted on 28 May 2012 | 12:58 pm

A dipicolylamine-appended cyclometalated iridium(III) complex: Synthesis, characterization and metal ions recognition

Publication year: 2012
Source:Inorganica Chimica Acta, Volume 390

Xianghong Li, Huajun Lan, Yuanbing Chen, Kangle Lv, Aiqing Zhang, Tao Huang

A new phosphorescent dye (complex 1) containing iridium cyclometalated complex as fluorophore and di(2-picolyl)amine (DPA), connected to the 4,4?-positions of the bipyridine unit through >CO, as recognition group was synthesized and characterized. The UV–Vis absorption and luminescence properties of 1 were investigated with heavy-metal ions as well as Zn²⁺, Cd²⁺, Co²⁺, Ni²⁺, Ag⁺, Fe²⁺, Mn²⁺, Hg²⁺, Pb²⁺ and Cu²⁺. The emission intensities of complex 1 were strongly quenched by the addition of Cu²⁺, Zn²⁺ and Hg²⁺. The binding constants (K s) and stoichiometry of complex 1 were calculated from luminescence titration data, with values of K s =3.09×10⁵ M^?1 (Cu²⁺), 5.75×10⁴ M^?1 (Zn²⁺) and 1.90×10⁴ M^?1 (Hg²⁺), respectively. Therefore, 1 exhibited high selectivity and efficient signaling behavior to Cu²⁺ over Zn(II), Hg(II) and other metal ions.

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Posted on 28 May 2012 | 12:58 pm

Synthesis, structural, thermal, and magnetic investigations of Co(II), Ni(II), and Mn(II) pyrophosphate chains

Publication year: 2012
Source:Inorganica Chimica Acta, Volume 389

Amanda E. Hoffman, Nadia Marino, Francesc Lloret, Miguel Julve, Robert P. Doyle

The reaction in water of cobalt(II), nickel(II) or manganese(II) chloride with 1,10-phenanthroline (phen) and sodium pyrophosphate (Na4P2O7) at low pH (?2) afforded three isostructural pyrophosphate complexes of an unprecedented one-dimensional typology, namely, {[M(phen)(H2O)(H2P2O7)]·H2O} n with M=Co(1), Ni(2) and Mn(3). The di-hydrogen-pyrophosphate anion featured in these complexes adopts a rare bidentate/monodentate bridging mode leading to chain propagation. This unusual bridging pathway produces a metal–metal intra-chain separation of about 6.6–6.7Å for 1–3, values much larger than the metal–metal distance across the classic bis-bidentate PPi in the parent homodinuclear complexes {[Co(phen)2]2(?-P2O7)}·6MeOH (1a), {[Ni(phen)2]2(H2O)(?-P2O7)}·27H2O (2a) and {[Mn(phen)2]2(H2O)(?-P2O7)}·13H2O (3a), corresponding to ca. 4.9, 5.0 and 4.7Å, respectively. Variable-temperature magnetic susceptibility measurements on polycrystalline samples of 1–3 revealed weak intrachain antiferromagnetic couplings [J =?0.93 (1), ?1.88 (2) and ?0.26cm^?1 (3)], consistent with previous data on the dinuclear complexes 1a–3a.

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Posted on 28 May 2012 | 12:58 pm

Synthesis, structure and oxidation of alkynes using a ?-oxo diiron complex with the ligand bis (1-(pyridin-2-ylmethyl)-benzimidazol-2-yl methyl) ether

Publication year: 2012
Source:Inorganica Chimica Acta, Volume 390

Raghvi Khattar, M.S. Hundal, Pavan Mathur

New ligand bis (1-(pyridin-2-ylmethyl)-benzimidazol-2-ylmethyl ether and its ?-oxo diferric complex has been synthesized and characterized. The dimeric [LClFe–O–FeCl3] has been characterized crystallographically, and shows that iron atoms occupy inequivalent coordination sites. One of the Fe (III) atom is coordinated by two benzimidazole nitrogens, one ether oxygen and bridging oxide oxygen, forming the equatorial plane while one Cl^? ion and the oxygen atom of a DMF molecule occupy the axial fifth and the sixth coordination positions. The second Fe (III) is tetrahedrally coordinated by three Cl^? ions and the bridging oxide oxygen O. The bridging oxide anion is unsymmerically coordinated to the two Iron (III) atoms. Oxidation of aromatic alkynes was investigated using this complex as catalyst with small amount of tert-butyl hydroperoxide (TBHP) and Hydrogen peroxide (H2O2) as an alternate source of oxygen. Isolated products were characterized by GC-Mass. Solvent, temperature, Stoichiometry and oxidant variation are studied and reaction conditions have been optimized. Dicarbonyl and ?,?-acetylenic ketone are the major product and depend on the nature of the alkyne employed.

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Posted on 28 May 2012 | 12:58 pm

Anion mediated diversity in the H-bonded assembly of a series of heteronuclear copper(II)/sodium(I) compounds

Publication year: 2012
Source:Inorganica Chimica Acta, Volume 390

Prasanta Bhowmik, Subrata Jana, Partha Pratim Jana, Klaus Harms, Shouvik Chattopadhyay

Three heteronuclear Cu(II)/Na(I) compounds, [Cu(vanpn)Na(NO3)(H2O)] (1), [Cu(vanpn)Na(N3)(CH3OH)] (2) and [Cu(vanpn)Na(NCS)(H2O)] (3) where H2vanpn= N,N?-(1,3-propylene)-bis(3-methoxysalicylideneimine), a well known compartmental Schiff base ligand, have been prepared and characterized by elemental analysis, IR and UV–Vis spectroscopy and single crystal X-ray diffraction studies. Compound 1 crystallises in monoclinic space group P21/n, compound 2 in triclinic $P\overline{1}$ and compound 3 in orthorhombic space group Pbca. In all the compounds, Cu atoms assume distorted square planar geometries whereas Na atoms exhibit distorted octahedral geometry. In compound 1, the nitrate ion is coordinated as a chelating ligand and essentially both the O atoms of the nitrate occupy one axial site. Variation of the counter anions leads to considerable change in the H-bonded supramolecular structures of the compounds. Compound 1 forms a dimer, compound 2 constitutes a chain and compound 3 forms a helix. Electrochemical electron transfer study reveals Cu(II)Cu(I) reduction in acetonitrile solution.

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Posted on 28 May 2012 | 12:58 pm

Prelim iii Editorial board

Publication year: 2012
Source:Inorganica Chimica Acta, Volume 389

Posted on 28 May 2012 | 12:58 pm

Molecular structures and spectroscopic studies of cationic metal–methylisonicotinate complexes with saccharinate counterions

Publication year: 2012
Source:Inorganica Chimica Acta, Volume 390

Esat Bozkurt, Hüseyin Ayaz, ?brahim Uçar, Bünyamin Karabulut

The crystal structures of [Co(methylisonicotinate)2(H2O)4](saccharinate)2 and [Ni(methylisonicotinate)2(H2O)4](saccharinate)2 complexes have been synthesized and characterized by spectroscopic, EPR and X-ray diffraction techniques. The XRD data have indicated that both the Co(II) and Ni(II) ions lie on an inversion center, having distorted octahedral coordination through four aqua ligands composing the basal plane and two trans nitrogen atoms from the monodentate methylisonicotinate ligands occupying the axial sites. The EPR spectra of these complexes have been studied in the temperature range between 113 and 300K in three mutually perpendicular planes. The EPR spectral results were discussed and compared in relation with the other compounds containing saccharinate and methylisonicotinate complexes.

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Posted on 28 May 2012 | 12:58 pm

Protagonists in Chemistry: Prof. Jon Zubieta

Publication year: 2012
Source:Inorganica Chimica Acta, Volume 389

Robert P. Doyle

Posted on 28 May 2012 | 12:58 pm

Solvent-regulated assembly of three new polymeric CdII 5-fluoroisophthalates with mono-, di-, and trinuclear nodes: Syntheses, structures, and luminescent properties

Publication year: 2012
Source:Inorganica Chimica Acta, Volume 390

Sheng-Chun Chen, Rui-Rui Qin, Zhi-Hui Zhang, Jing Qin, Hai-Bo Gao, Fu-An Sun, Ming-Yang He, Qun Chen

Three new polymeric Cd^II complexes, [Cd(fip)(MeOH)3] n (1), {[Cd2(fip)2(H2O)5]·4H2O} n (2), and {[Cd3(fip)4(H2O)2][Cd(DMF)2(H2O)4]·2DMF} n (3), have been prepared from the reactions of Cd^II acetate with a rigid fluorinated ligand 5-fluoroisophthalic acid (H2fip) under different solvent systems. Complex 1 shows a 1D zigzag coordination chain with a mononuclear [Cd(COO)(MeOH)3] unit, and complex 2 displays a 2D neutral layered structure containing a dinuclear [Cd2(COO)4(H2O)5] entity, while complex 3 presents a 2D anionic coordination network with the linear trinuclear [Cd3(COO)8(H2O)2] clusters as the linking nodes. The results clearly suggest that the judicious choice of solvent systems does play a critical role in the construction of coordination frameworks with distinct connectivity and dimensionality. The spectroscopic, thermal, and luminescent properties of 1–3 have also been investigated.

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Posted on 28 May 2012 | 12:58 pm

Metal complexes of thiosemicarbazones for imaging and therapy

Publication year: 2012
Source:Inorganica Chimica Acta, Volume 389

Jonathan R. Dilworth, Rebekka Hueting

This review gives an account of the coordination chemistry of thiosemicarbazone ligands with three (tridentate) or four (tetradentate) potential donor atoms. The syntheses and structures of the ligands complexes are described according to the donor atom combinations and metals involved. The review also covers the biological activities of the ligands and complexes in the context of their applications as therapeutic or diagnostic PET or SPECT imaging agents.

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Recent developments in the design of bifunctional chelators for metal-based radiopharmaceuticals used in Positron Emission Tomography

Publication year: 2012
Source:Inorganica Chimica Acta, Volume 389

Mark D. Bartholomä

In recent years, Positron Emission Tomography (PET) has become a practical, high performance clinical imaging modality for visualization of biological process within the living system. For radiolabeling of targeting vectors, ideally determining the biological fate of the radiolabeled bioconjugate, non-traditional metal-based PET radioisotopes are of particular interest as they offer certain advantages over traditional PET radioisotopes such as longer half-lives that allow delayed imaging or availability by commercial generator systems apart from on-site cyclotron production. However, for the incorporation of the radiometal into the targeting vector, a bifunctional chelator is needed that tightly binds the radiometal at one terminus while the second terminus serves for the covalent conjugation to the biomolecule. Conjugation of a metal chelate functionality to a biovector, however, may impact the in vivo distribution of the biomolecule. This review summarizes the recent developments of bifunctional chelates for two important PET radiometals, copper-64 and gallium-68, and discusses their coordination chemistry in relation to in vivo stability and pharmacokinetics.

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Posted on 28 May 2012 | 12:58 pm

Understanding how the platinum anticancer drug carboplatin works: From the bottle to the cell

Publication year: 2012
Source:Inorganica Chimica Acta, Volume 389

Anthony J. Di Pasqua, Jerry Goodisman, James C. Dabrowiak

Carboplatin, a platinum anticancer drug used to treat many types of human cancer, contains a bidentate dicarboxylate chelate leaving ligand, a structural feature that makes it much less chemically reactive than the first-generation platinum anticancer drug cisplatin, which contains two monodentate chloride leaving ligands. In water, carboplatin exists in a monomer–dimer equilibrium with an association constant of K (M^?1)?391, a property that accounts for the long-term stability of its ready-to-use infusion solution. When administered in the clinic, carboplatin is believed to exert its biological effects by interacting with genomic DNA and proteins. The slower substitution kinetics of carboplatin, compared to cisplatin, has prompted investigators to focus on mechanisms by which the compound can be activated in vivo. Carbonate, which is in equilibrium with hydrogen carbonate, carbonic acid, and dissolved carbon dioxide, is ubiquitous in biological systems, and is found in high concentrations in the blood, the interstitial fluid, and the cytosol. Activation of carboplatin by carbonate, CO3 ^2? (k 1 =2.04±0.81×10^?6 in 24mM carbonate buffer, pH 7.5 at 37°C), for example, leads to the formation of platinum species that are more cytotoxic than the parent drug. This short review focuses on the reason for the unusual stability of carboplatin in its aqueous ready-to-use infusion solution, describes the reactions of the drug with biologically common nucleophiles and summarizes the activation chemistry that make the drug more reactive toward substances present in the biological system.

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Posted on 28 May 2012 | 12:58 pm

Spectroscopic and electrochemical properties of mononuclear Mn(III) complex and of binuclear di-?-oxo bridged Mn(III) and Mn(IV) complex with isocyclam

Publication year: 2012
Source:Inorganica Chimica Acta, Volume 390

D. Tomczyk, G. Andrijewski, L. Nowak, P. Urbaniak, D. Sroczy?ski

trans-[Mn^III isocyclamCl2]Cl·2H2O and [Mn^IIIMn^IV(?-O)2 isocyclam 2](ClO4)3·2H2O (isocyclam =1,4,7,11-tetraazacyclotetradecane) were synthesised and analysed. Coordination geometry of both of these complexes was estimated with IR and electronic spectroscopy as trans-pseudo-octahedral for the first one and cis-pseudo-octahedral with two oxygen bridges for the other one. Magnetic properties of complexes were characterised as high-spin and antiferromagnetic, respectively. Cyclic voltammetry measurements of neutral aqueous solutions showed the possibility of oxidation of both complexes to [Mn^IVMn^IV(?-O)2 isocyclam 2]⁴⁺. Mechanism of oxidation of mononuclear complex including its isomerisation process was proposed. Formal potentials and transfer coefficients were calculated.

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Posted on 28 May 2012 | 12:58 pm

Copper(II) complexes with 2,5-bis(2-pyridyl)pyrazine and oxalate and croconate: Synthesis, crystal structure and magnetic properties

Publication year: 2012
Source:Inorganica Chimica Acta, Volume 389

Abdeslem Bentama, Oliver Schott, Jesús Ferrando-Soria, Salah-Eddine Stiriba, Jorge Pasán, Catalina Ruiz-Pérez, Miguel Julve

Two new copper(II) complexes of formula [Cu2(2,5-dpp)(C2O4)2(H2O)4] (1) and [Cu2(2,5-dpp)(C5O5)2(H2O)4]·3H2O (2) [2,5-dpp=2,5-bis(2-pyridyl)pyrazine, C2O4 ^2? =oxalate and C5O5 ^2? =croconate (dianion of 4,5-dihydroxycyclopent-4-ene-1,2,3-trione)] have been prepared and their structures determined by X-ray crystallographic methods. Compounds 1 and 2 are dinuclear complexes where the 2,5-dpp molecule acts as a bis-bidentate bridge between the two copper(II) ions, the electroneutrality being achieved by the presence of bidentate oxalate (1) and croconate (2) ligands. Each copper(II) ion exhibits an elongated octahedral CuN2O4 environment with two nitrogen atoms from 2,5-dpp and two oxalate (1)/croconate (2)-oxygens occupying the equatorial positions and two water molecules (1 and 2) in the axial sites. The values of the copper–copper separation across bridging 2,5-dpp are 6.773(2) (1) and 6.728(2)Å (2). Variable-temperature magnetic susceptibility measurements of 1 and 2 in the temperature range 1.9–300K reveal the occurrence of weak intramolecular antiferromagnetic interactions. The poor ability of the 2,5-dpp molecule to mediate significant magnetic interactions in its copper(II) complexes when adopting the bis-bidentate coordination agrees with that exhibited by the related polypyridine ligand 2,3-bis(2-pyridyl)pyrazine (2,3-dpp) but it contrasts with the better efficiency of the pyrazine (pyz) and 2,3,5,6-tetrakis(2-pyridyl)pyrazine (tppz) bridging ligands.

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Posted on 28 May 2012 | 12:58 pm

Modulation of ligand fluorescence by the Pt(II)/Pt(IV) redox couple

Publication year: 2012
Source:Inorganica Chimica Acta, Volume 389

Justin J. Wilson, Stephen J. Lippard

The dangling carboxylic acid moiety of the known platinum(II) complex, [Pt(edma)Cl2] (edma=ethylenediaminemonoacetic acid), was functionalized via amide coupling chemistry with benzyl amine and dansyl ethylenediamine to afford the derivatives [Pt(edBz)Cl2] (1) and [Pt(edDs)Cl2] (2). Subsequent oxidation of these platinum(II) complexes with iodobenzene dichloride in DMF yielded the respective platinum(IV) analogs, [Pt(edBz)Cl4] (3) and [Pt(edDs)Cl4] (4). All four platinum complexes were characterized by multinuclear NMR spectroscopy, IR spectroscopy, electrospray ionization mass spectrometry, and elemental analysis. In addition, compounds 1 and 3 were structurally characterized by X-ray crystallography. The photophysical properties of the compounds bearing the fluorescent dansyl moiety, 2 and 4, were evaluated. The emission quantum yields of 2 and 4 in DMF are 27% and 1.6%, respectively. This large difference in emission efficiency indicates that the platinum(IV) center in 4 is more effective at quenching the dansyl-based fluorescence than the platinum(II) center in 2. Time-dependent density functional theory calculations indicate that 4 has several low-lying singlet excited states that energetically lie below the primary radiation-accessible excited state of the dansyl fluorophore. These low-energy excited states may offer non-radiative decay pathways that lower the overall emission quantum yield. Treatment of 4 with biologically relevant reducing agents in pH 7.4 phosphate-buffered saline induces a 6.3-fold increase in emission intensity. These results demonstrate that 4 and future derivatives thereof may be useful for imaging the reduction of platinum(IV) complexes in living systems, chemistry of importance for evolving platinum-based anticancer drug strategies.

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Posted on 28 May 2012 | 12:58 pm

Copper(II) halide coordination complexes and salts of 3-halo-2-methylpyridines: Synthesis, structure and magnetism

Publication year: 2012
Source:Inorganica Chimica Acta, Volume 389

Mahmoud Abdalrahman, Christopher P. Landee, Shane G. Telfer, Mark M. Turnbull, Jan L. Wikaira

Two families of compounds have been prepared from the reaction of 3-X?-2-methylpyridine with CuX2 (X, X?=Cl, Br) in the presence or absence of HX. Four salts, (3-X?-2-methylpyridinium)2CuX4 were prepared, three of which crystallize in the orthorhombic space group Pbcn while the fourth (X=Br and X?=Cl) crystallizes in the monoclinic space group C2/c. All four neutral compounds of formula (3-X?-2-methylpyridine)2CuX2 crystallize in the space group $P\overline{1}$. Of these, three form weakly bridged chains via long Cu?X contacts, while the fourth (X=X?=Cl) forms centrosymmetric dimers. Most of the complexes exhibit only very weak antiferromagnetic interactions and can be modeled as weak uniform chains. Compound 4, (3-Cl-2-methylpyridinium)2CuBr4, shows behavior that models an isolated 2D-Heisenberg antiferromagnetic layer with J =?5.09(2)K, while compound 7, (3-Cl-2-methylpyridine)2CuCl2, crystallizes as a bichloride bridged centrosymmetric dimer with J =?29.31(6)K.

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Posted on 28 May 2012 | 12:58 pm

Reactions of N-heterocyclic ligands with substitutionally labile organometallic complexes, [(?5-C5R5)Fe(CO)2E]BF4

Publication year: 2012
Source:Inorganica Chimica Acta, Volume 390

Cyprian M. M’thiruaine, Holger B. Friedrich, Evans O. Changamu, Muhammad D. Bala

The ether complexes [Cp(CO)2Fe(OEt2)]BF4 (Cp=?⁵-C5H5) (1) and [Cp^?(CO)2Fe(THF)]BF4 (Cp^? =?⁵-C5(CH3)5) (2) react with 1,3,5,7-tetraazaadamantane (HMTA) to give stable water-soluble dinuclear complexes [{(?⁵-C5R5)(CO)2Fe}2(?-HMTA)](BF4)2 (R=H; R=CH3) and mononuclear complexes [(?⁵-C5R5)(CO)2Fe(HMTA)]BF4 (R=H; R=CH3). The reaction of 1 with 1,4-diazabicyclo[2.2.2]octane (DABCO) gave good yields of the dinuclear and mononuclear complexes, [{Cp(CO)2Fe}2(?-DABCO)](BF4)2 (6a) and [Cp(CO)2Fe(DABCO)]BF4 (6b), respectively, depending on reagent ratios. Similar reactions with 2 gave very low yields of the mononuclear complex [Cp^?(CO)2Fe(DABCO)]BF4 (6c) as the only product. The reactions of [Cp(CO)2Fe(HMTA)]BF4 (3b) and [Cp^?(CO)2Fe(HMTA)]BF4 (4b) with NaBPh4 in acetone proceeded smoothly at room temperature to give the corresponding BPh4 ^- salts. Reaction of 4b with 1 at room temperature gave the dinuclear complex [{Cp(CO)2Fe}2(?-HMTA)](BF4)2 (3a) as the major product, while the same reaction conducted at 0°C led to the unstable mixed ligand complex [{Cp(CO)2Fe}(?-HMTA){Fe(CO)2Cp^?}](BF4)2. The reactions of 1 and 2 with 1-methylimidazole (1-meIm) gave high yields of [(?⁵-C5R5)(CO)2Fe(1-meIm)]BF4 (R=H (7); R=CH3 (8)), of which the NMR, IR and single crystal X-ray studies reveal the coordination of 1-methylimidazole to be via the ‘pyridine nitrogen’ of the imidazole ring. Single-crystal X-ray diffraction studies reveal that compounds 3a and 8 crystallize in the orthorhombic P212121 and Pna21 space groups, respectively. Compound 7 however, crystallized in the monoclinic P21/c space group with three independent molecular cations and anions each in the asymmetric unit.

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Posted on 28 May 2012 | 12:58 pm

Synthesis, structure and magnetic properties of two organically-templated coordination polymers, {[EDAH2][M1M2F2(SO4)2(H2O)2]}n (M1=M2=NiII and M1=CoII, M2=NiII)

Publication year: 2012
Source:Inorganica Chimica Acta, Volume 389

C.M. Nagaraja, Tapas Kumar Maji, C.N.R. Rao

Two isostructural, organically-templated, 2D coordination polymers, one containing Ni^II and another containing Co^II and Ni^II ions with the general formulae, {[EDAH2][M1M2F2(SO4)2(H2O)2]} n , (EDA=ethylenediamine, M1 =M2 =Ni^II (1), and M1 =Co^II, M2 =Ni^II (2)) have been synthesized and structurally characterized. 1 and 2 consist of a 1D chain bridged by F^? ion, [M–F–M] n which is interconnected by SO4 ^2? tetrahedra forming a 2D [Ni2F2(SO4)2(H2O)2] n ^2? or [CoNiF2(SO4)2(H2O)2] n ^2? corrugated sheet which are templated by diprotonated ethylenediamine [EDAH2] cation. Temperature-dependent magnetic measurements reveal the presence of spin-canted antiferromagnetism in both 1 and 2. 1 behaves like a soft magnet with a small magnetic hysteresis with a coercive field (Hc ) of 0.46kOe and a remnant magnetization (MR ) of 0.09 ? B. 2, on the other hand exhibits relatively a hard magnet like behavior with large magnetic hysteresis with Hc =8.74kOe and MR =0.76 ? B. The difference in magnetic behaviors of 1 and 2 is attributed to the difference in single-ion magnetic anisotropy and spin magnitudes of Ni^II (S =1) and Co^II (S =3/2) ions.

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Posted on 28 May 2012 | 12:58 pm

Encapsulation of Keggin-type anions in reduced molybdenum–iron-type Keplerates as a general phenomenon

Publication year: 2012
Source:Inorganica Chimica Acta, Volume 389

Ana Maria Todea, Ahmed Jasim M. Al-Karawi, Thorsten Glaser, Stephan Walleck, Lise-Marie Chamoreau, René Thouvenot, Pierre Gouzerh, Achim Müller

Upon standing in air at room temperature, acidified aqueous solutions (pH 2) obtained by dissolving sodium molybdate, iron(II) chloride, acetic acid and potassium dodecatungstoborate led to the formation of greenish thin plate crystals (1) containing discrete clusters. Upon drying 1 at room temperature crosslinking of the clusters occurs in a solid-state reaction which leads to compound 2. Based on crystallographic studies of 1 and on extensive physical characterization (vibrational, NMR, Mössbauer spectra and magnetic susceptibility measurements) of 2, it was shown that compounds 1 and 2 contain reduced spherical {Mo72Fe30} Keplerate-type shells encapsulating non-reduced tungstoborate Keggin-type anions. The properties and structures of these compounds are compared to related hybrid structures containing in principle easier reducible molybdophosphate or molybdosilicate cores. According to the results the present type of encapsulation can be considered as a general phenomenon.

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Posted on 28 May 2012 | 12:58 pm

Synthesis and magnetic properties of a series of 3d/4f/3d heterometallic trinuclear complexes incorporating in situ ligand formation

Publication year: 2012
Source:Inorganica Chimica Acta, Volume 389

Anthony S.R. Chesman, David R. Turner, Boujemaa Moubaraki, Keith S. Murray, Glen B. Deacon, Stuart R. Batten

The dicyanonitrosomethanide (dcnm) ligand undergoes an in situ transition metal promoted nucleophilic addition of methanol to a nitrile group to form cyano(imino(methoxy)methyl)nitrosomethanide (cmnm) in the formation of the 3d/4f heterometallic complexes (Me4N)[{Ni(cmnm)3}2Ln(cmnm)2] (1Ln; 1Ln = 1La, 1Ce, 1Pr, 1Nd, 1Sm). A change in the counter-ions of the metal and ligand salts employed under alternate reaction conditions results in the formation of (Et4N)2[{Ni(cmnm)3}2Ln(dcnm)2](ClO4) (2Ln; 2Ln = 2La, 2Ce), in which unreacted dcnm ligands are coordinated to the central lanthanoid. In both types of complexes three cmnm ligands chelate to a nickel metal centre to form a [Ni(cmnm)3] metalloligand. Two of these metalloligands are then bound to a central lanthanoid via the nitroso oxygen atoms, resulting in a trinuclear complex in which each nickel cation is connected to the lanthanoid by three bridging nitroso groups. Variable temperature magnetic susceptibilities on these {Ni(S=1), Ln(f ⁰ to f ⁵), Ni(S=1)} spin systems reveal very weak to zero Ln–Ni or Ni–Ni exchange coupling with the thermal depopulation between Stark levels on the Ln centres being of similar magnitude, and the Ni2Ce and Ni2Pr cases giving strongest evidence for exchange coupling.

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Posted on 28 May 2012 | 12:58 pm

Synthesis, structure, DNA binding and photonuclease activity of a nickel(II) complex with a N,N?-Bis(salicylidene)-9-(3,4-diaminophenyl)acridine ligand

Publication year: 2012
Source:Inorganica Chimica Acta, Volume 390

Mariappan Mariappan, Masahiko Suenaga, Abhik Mukhopadhyay, Bhaskar G. Maiya

A new class of salen functionalized novel ligand N,N?-Bis(salicylidene)-9-(3,4-diaminophenyl)acridine, H2daasal (two potential intercalators, salen and acridine, which are linked together via C–C bond) and its metal complex [Ni(daasal)] have been synthesized and characterized by X-ray diffraction, elemental analysis, UV–Vis, IR, ¹H NMR, MALDI-TOF mass spectrometry and cyclic voltammetry methods. From the crystal structure, the salphen moiety is not coplanar with the acridine ring, having a dihedral angle of 68° and 76° in both H2daasal and [Ni(daasal)], respectively. [Ni(daasal)] shows a reversible oxidation cyclic voltammetric response near 1.03V versus SCE in CH3CN (0.1M TBAP) assignable to the Ni(II)/Ni(III) couple. The interaction of these compounds with calf-thymus (CT) DNA was examined using spectroscopic and viscosity measurements. These studies reveal that both compounds bind to CT DNA via an intercalative mode. Molecular-modeling studies also support an intercalative mode of binding to the model duplex d(CGCAATTGCG)2 possibly from the major groove with a slight preference for GC rich region. Additionally, [Ni(daasal)] promotes the cleavage of plasmid pBR322 DNA upon irradiation under terminal oxidant Oxone.

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Posted on 28 May 2012 | 12:58 pm

Synthesis and structural characterisation of a Co(II) coordination polymer incorporating a novel dicarboxy-Trögers base/bis-pyrazole mixed ligand system

Publication year: 2012
Source:Inorganica Chimica Acta, Volume 389

Chris S. Hawes, Christopher M. Fitchett, Stuart R. Batten, Paul E. Kruger

A cobalt(II) coordination polymer, [Co(L1)(H2L2)]·2.5H2O, 1, has been prepared via the hydrothermal reaction of cobalt(II) chloride with the novel dicarboxy-Tröger’s base ligand 2,8-dicarboxy-6H,12H-5,11-methano-dibenzo[b,f][1,5]diazocine, H2L1, and the bis-pyrazole ligand 4,4?-methylenebis-(3,5-dimethylpyrazole), H2L2. The structure of 1 contains 2D (4,4) networks showing 2D?3D parallel interpenetration, whereby adjacent 2D sheets interlock through the apertures defined by the cleft-like Tröger’s base ligand, to realise an overall 3D entanglement. The interlocking also forms one-dimensional solvent filled channels which are easily disturbed on drying resulting in framework collapse. The crystal structure of H2L1 is also reported, and represents a rare example of homochiral hydrogen bonded [6,4] dia networks interpenetrated by their enantiomeric partner frameworks.

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Posted on 28 May 2012 | 12:58 pm

Synthesis and characterization of new trinuclear copper complexes

Publication year: 2012
Source:Inorganica Chimica Acta, Volume 389

Reza A. Ghiladi, Arnold L. Rheingold, Maxime A. Siegler, Kenneth D. Karlin

This report describes our approach towards modeling the copper cluster active sites of nitrous oxide reductase and the multicopper oxidases/oxygenases. We have synthesized two mesitylene-based trinucleating ligands, MesPY1 and MesPY2, which employ bis(2-picolyl)amine (PY1) and bis(2-pyridylethyl)amine (PY2) tridentate copper chelates, respectively. Addition of cuprous salts to these ligands leads to the isolation of tricopper(I) complexes [(Mes-PY1)Cu^I 3(CH3CN)3](ClO4)3·0.25Et2O (1) and [(Mes-PY2)Cu^I 3](PF6)3 (3). Each of the three copper centers in 1 is most likely four-coordinate, with ligated acetonitrile as the fourth ligand; by contrast, the copper centers in 3 are three-coordinate, as determined by X-ray crystallography. The synthesis of [(Mes-PY1)Cu^II 3(CH3CN)2(CH3OH)2](ClO4)6·(CH3OH) (2) was accomplished by addition of three equivalents of the copper(II) salt, Cu(ClO4)2·6H2O, to the ligand. The structure of 2 shows that two of the copper centers are tetracoordinate (with MeCN solvent ligation), but have additional weak axial (fifth ligand) interactions with the perchlorate anions; the third copper is unique in that it is coordinated by two MeOH solvent molecules, making it overall five-coordinate. For complexes 2 and 3, one copper ion center is located on the opposite side of the mesitylene plane as the other two. These observations, although in the solid state, must be taken into account for future studies where intramolecular tricopper(I)/O2 (or other small molecules of interest) interactions in solution are desirable.

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Posted on 28 May 2012 | 12:58 pm

Alkaline earth metal di- and triphenylmethanides: Analysis of ion association modes

Publication year: 2012
Source:Inorganica Chimica Acta, Volume 389

Marites A. Guino-o, Ana Torvisco, Weijie Teng, Karin Ruhlandt-Senge

A family of alkaline earth metal di- and triphenylmethanides was prepared and examined to illustrate ion association trends and associated reactivity in dependence of metal, coligand and ligand delocalization. To this effect, we are reporting the contact molecules Ba(18-crown-6)(CHPh2)2 and Ba(dme)2(CHPh2)2 (DME, 1,2-dimethoxyethane), the dissociated ions [Ba(hmpa)6][R]2, R=CHPh2, CPh3 (HMPA, hexamethylphosphoramide), in addition to two compounds with one metal bound anion, and an unassociated one, [Ca(18-crown-6)(N(SiMe3)2)][R], R=CHPh2, CPh3. We are also reporting a highly unusual lithium enolate, [Li2(OCHCH2)(pmdta)2][CHPh2] (PMDTA, N,N,N?,N?,N?-pentamethyldiethylenetriamine), obtained en route to the target compounds via THF scission chemistry.

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Posted on 28 May 2012 | 12:58 pm

The interaction between heteroditopic pyridine–nitrogen NHC with novel sulfur NHC ligands in palladium(0) derivatives: Synthesis and structural characterization of a bis-carbene palladium(0) olefin complex and formation in solution of an alkene–alkyne mixed intermediate as a consequence of the ligands hemilability

Publication year: 2012
Source:Inorganica Chimica Acta, Volume 390

Luciano Canovese, Fabiano Visentin, Carlo Levi, Claudio Santo, Valerio Bertolasi

We have synthesized a new class of heteroditopic chelating ligands bearing the phenylthiomethyl group and variously substituted imidazole derivatives and the corresponding complexes [Pd(?²-ma)(R-NHC-CH2-SPh) (ma=maleic anhydride; R=methyl, mesityl, di-i-propylphenyl). We have compared their chemical characteristics and reactivity with those of similar palladium(0) complexes bearing the R-NHC-CH2-Py ligands. The hemilability of the above-mentioned moieties is apparent when their palladium derivatives react with an excess of the same or different heteroditopic ligands. In these cases, we obtained complexes bearing maleic anhydride and two mono-coordinated heteroditopic ligands bound to the same metal center. However, at variance with the generally accepted opinion, precipitation of AgBr does not warrant the quantitative formation of the bis-heteroditopic Pd(0) derivative and in some cases, a reaction involving a heterogeneous equilibrium is observed. The reaction of the palladium(0) carbene–sulfur or carbene–nitrogen complexes with the alkyne dimethyl-2-butynedioate (dmbd) to give palladacyclometallate derivatives is not always warranted and formation of the intermediate [Pd(?²-ma)(?²-dmdb)(?¹-Mes-NHC-CH2-SPh)] is detected only in one case. Finally, we have carried out a diffractometric study on the solid-state structures of two derivatives and in particular we describe the configurations of the complex [Pd(?²-ma)(?¹-Me-NHC-CH2-SPh)2] and of [Pd(?²-ma)(Me-NHC-CH2-SPh)].

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Posted on 28 May 2012 | 12:58 pm

Reversible dioxygen binding and arene hydroxylation reactions: Kinetic and thermodynamic studies involving ligand electronic and structural variations

Publication year: 2012
Source:Inorganica Chimica Acta, Volume 389

Kenneth D. Karlin, Christiana Xin Zhang, Arnold L. Rheingold, Benedikt Galliker, Susan Kaderli, Andreas D. Zuberbühler

Copper–dioxygen interactions are of intrinsic importance in a wide range of biological and industrial processes. Here, we present detailed kinetic/thermodynamic studies on the O2-binding and arene hydroxylation reactions of a series of xylyl-bridged binuclear copper(I) complexes, where the effects of ligand electronic and structural elements on these reactions are investigated. Ligand 4-pyridyl substituents influence the reversible formation of side-on bound ?-?²:?²-peroxodicopper(II) complexes, with stronger donors leading to more rapid formation and greater thermodynamic stability of product complexes [Cu^II 2(^RXYL)(O2 ^2?)]²⁺. An interaction of the latter with the xylyl ?-system is indicated. Subsequent peroxo electrophilic attack on the arene leads to C–H activation and oxygenation with hydroxylated products [Cu^II 2(^RXYLO^–)(^?OH)]²⁺ being formed. A related unsymmetrical binucleating ligand was also employed. Its corresponding O2-adduct [Cu^II 2(UN)(O2 ^2?)]²⁺ is more stable, but primarily because the subsequent decay by hydroxylation is in a relative sense slower. The study emphasizes how ligand electronic effects can and do influence and tune copper(I)–dioxygen complex formation and subsequent reactivity.

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Posted on 28 May 2012 | 12:58 pm

Small molecule inhibitors of PSMA incorporating technetium-99m for imaging prostate cancer: Effects of chelate design on pharmacokinetics

Publication year: 2012
Source:Inorganica Chimica Acta, Volume 389

Kevin P. Maresca, Shawn M. Hillier, Genliang Lu, John C. Marquis, Craig N. Zimmerman, William C. Eckelman, John L. Joyal, John W. Babich

Single amino acid chelate (SAAC) systems for the complexation of the M(CO)3 moiety (M=Tc/Re) have been successfully incorporated into novel synthetic strategies for radiopharmaceuticals and evaluated in a variety of biological applications. However, the lipophilicity of the first generation of ^99mTc(CO)3 complexes has resulted in substantial hepatobiliary uptake when examined either as lysine derivatives or integrated into biologically active small molecules and peptides. Here, we designed, synthesized, and evaluated novel polar functionalized imidazole derived SAAC systems (SAAC II) which have been chemically modified to promote overall ^99mTc(CO)3L3 complex hydrophilicity with the intent of reducing non-target effects and enhancing renal clearance of prostate specific membrane antigen (PSMA) targeting small molecules. The ^99mTc-labeled compounds were prepared, purified, and evaluated for stability, lipophilicity, and tissue distribution in LNCaP xenograft mice. The Glu-urea-Lys-C11 analogs were prepared with a variety of chelators to form (19R,23S)-1-(X)-2-((Y)methyl)-13,21-dioxo-2,14,20,22-tetraazapentacosane-19,23,25-tricarboxylic acid where X=Y=(methyl)pyridin-2-yl (6), X=Y=(methyl)-1H-imidazol-2-yl (7), X=(methyl)pyridin-2-yl, Y=carboxymethyl (8), X=Y=1-(carboxymethyl)-1H-imidazol-2-yl (9), X=1-(carboxymethyl)-1H-imidazol-2-yl, Y=carboxymethyl (10), and X=Y=1-(1-(2-(bis(carboxymethyl)amino)-2-oxoethyl)-1H-imidazol-2-yl)-2-((1-(2-(bis(carboxymethyl)amino)-2-oxoethyl)-1H-imidazol-2-yl) (11). ^99mTc labeling was achieved at ligand concentrations as low as 10^?6 M and the complexes were stable (>90%) for 24h. These new SAAC II chelators were evaluated for their influence on binding of the Glu-urea-Lys-C11 analogs to PSMA-positive LNCaP cells and compared to pyridine- and N-methylimidazole-containing SAAC ligands. Tissue distribution of the ^99mTc-complexes containing the more polar chelators, 9 and 11, demonstrated decreased liver (<2% ID/g) and increased LNCaP tumor (>11% ID/g) accumulation at 1h post-injection.

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Posted on 28 May 2012 | 12:58 pm

The preparation and characterization of functionalized carboranes and Re/Tc-metallocarboranes as platforms for developing molecular imaging probes: Structural and cage isomerism studies

Publication year: 2012
Source:Inorganica Chimica Acta, Volume 389

Anika S. Louie, Laura E. Harrington, John F. Valliant

A study of the structure and reactivity of a series of carborane ligands [(RC2B9H11)^?] towards Re(I) and ^99mTc(I) was undertaken in which the arising products [(M(CO)3RC2B9H10)^?, M=Re, ^99mTc] can be used as platforms to develop organometallic molecular imaging agents. Synthetic methods are reported that produce good yields of the target ligands and metal complexes where the organometallic complexes were prepared in aqueous solvents at both the macroscopic scale and at the tracer level. NMR and X-ray crystallography studies confirmed the structures of the closo and nido-ligands and demonstrated that the rhenacarborane complexes exist as 3,1,2 and/or 2,1,8 isomers where the product distribution depends upon on the steric bulk and electronic influence of the substituent linked to the carbon atom of the carborane cage. Experiments at the tracer level with ^99mTc(I) demonstrated for one ligand a difference in the ratio of isomers produced and the reactivity of the ligands compared to that for Re(I). Data is also presented to show for the first time that a 3,1,2-technetium carborane forms initially during radiolabeling and then upon heating isomerizes to the more stable 2,1,8 isomer. The comparable process is not observed for rhenium. The log D values for the technetium complexes were also measured and are within the range needed to cross the blood–brain-barrier making the reported compounds viable candidates for imaging key targets in the central nervous system.

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Posted on 28 May 2012 | 12:58 pm

Blue fluorescence from the ligand and yellow phosphorescence from the iridium complex: High-efficiency wet-processed white organic light-emitting device

Publication year: 2012
Source:Inorganica Chimica Acta, Volume 390

Fang-Fang Yu, He-Liang Fan, Hai-Fang Huang, Qian-Yong Cao, Yan-Feng Dai, Xi-Cun Gao, Yu-Zhu Shang, Min-Yan Zhang, Li Long, Hong Xu, Xi-Feng Li, Bin Wei

We synthesized four carbazole modified blue-emitting fluorescent ligands. These ligands coordinated with Ir³⁺ and four yellow-emitting phosphorescent complexes were obtained. A high-efficiency (current efficiency 20.6cd/A) yellow electrophosphorescence device was wet-fabricated using the complex as a guest. The ligands can harvest and transfer energy to the complexes and a high efficiency (?18cd/A) white-light emitting device (CIE 0.31, 0.39) was obtained using the ligand as the blue-fluorescence emitter and the complex as the yellow-phosphorescence emitter. Therefore, the ligand can be a coordinator, an emitter and partly, a host. This is beneficial to device efficiency and saving cost for large-scale manufacturing.

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Posted on 28 May 2012 | 12:58 pm

The importance of London dispersion forces in crystalline magnesium nitrate hexahydrate

Publication year: 2012
Source:Inorganica Chimica Acta, Volume 389

Ewelina M. Witko, William D. Buchanan, Timothy M. Korter

The role of London dispersion forces in crystalline magnesium nitrate hexahydrate [Mg(NO3)2·6H2O] has been investigated using terahertz spectroscopy and solid-state density functional theory modeling. The solid-state simulations were augmented with semi-empirical London dispersion corrections and revealed that such corrections are of negligible importance in this ionic solid. The comparison of the simulated and experimental crystal structures indicated a London force correction magnitude of less than 10% of that required in organic molecular solids of similar size and complexity. While London forces are certainly present in magnesium nitrate hexahydrate, electrostatic forces clearly dominate the intermolecular interactions governing its crystalline structure and dynamics.

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Posted on 28 May 2012 | 12:58 pm

Ionic and electronic properties of oxo-vanadium arsenate and phosphate frameworks

Publication year: 2012
Source:Inorganica Chimica Acta, Volume 389

Q. Yuan, Y. Zhang, S. Green, E. Gihana, V. Soghomonian

Electrically conducting zeolite-like frameworks are largely unstudied as electronic materials, but may offer new avenues in energy applications, ranging from electrical energy storage to catalysis. We present two zeolite-like framework materials, a vanadium arsenate [(As6V15O51)^?9]?, compound (1), and a vanadium phosphate [(P6V15O51)^?9]?, compound (2), their syntheses, and physical and electrical characterization. We compare the electrical characteristics of the two compounds through the measurements of conductivity as a function of temperature and extra-framework constituents. Our results indicate that compound (1) is a mixed conductor with framework electronic conduction and ionic conduction associated with the extra-framework constituents. Compound (2), in contrast, shows only ionic conductivity. Probing the electronic properties of zeolite-like mixed conductors paves the way for the innovative use of these materials.

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Posted on 28 May 2012 | 12:58 pm

Effect of aliphatic dicarboxylate tether on topology in luminescent cadmium coordination polymers containing bis(4-pyridylformyl)piperazine

Publication year: 2012
Source:Inorganica Chimica Acta, Volume 389

Amy L. Pochodylo, Robert L. LaDuca

Hydrothermal synthesis has generated a series of luminescent cadmium aliphatic dicarboxylate coordination polymers containing the neutral multitopic bis(4-pyridylformyl)piperazine (bpfp) ligand, which were characterized by single-crystal X-ray diffraction, luminescence spectroscopy. {[Cd(suc)(bpfp)(H2O)]·2H2O} n (1, suc=succinate) has a simple yet very rare 4-connected 6⁵8 layered topology. {[Cd(dmg)(bpfp)(H2O)]·H2O} n (2, dmg=2,2-dimethylglutarate) also shows a 4-connected net, but with a 3-fold interpenetrated sra 4²6³8 topology. {[Cd(Hemg)2(bpfp)(H2O)]·2H2O} n (3, emg=3-ethyl, 3-methylglutarate) is a simple 1-D chain coordination polymer. {[Cd2(adp)(bpfp)2(H2O)2](ClO4)2·2H2O} n (4, adp=adipate) has {Cd2O2} dimeric units linked by adp and exotridentate bpfp ligands into a rare (3,8)-connected tfz-d binodal topology. The oxoanion free derivative [Cd(adp)(bpfp)] n (5) shows a non-interpenetrated 6-connectd pcu topology.

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Posted on 28 May 2012 | 12:58 pm

Stereospecific ligands and their complexes. Part X: Synthesis, characterization and in vitro antitumoral activity of platinum(IV) complexes with O,O?-dialkyl-(S,S)-ethylenediamine-N,N?-di-2-(4-methyl)pentanoate ligands

Publication year: 2012
Source:Inorganica Chimica Acta, Volume 390

Jelena M. Vuji?, Goran N. Kalu?erovi?, Bojana B. Zmejkovski, Marija Milovanovi?, Vladislav Volarevi?, Nebojša Arsenijevi?, Tatjana P. Stanojkovi?, Sre?ko R. Trifunovi?

Synthesis of four new platinum(IV) complexes 1–4, with bidentate N,N?-ligand precursors O,O?-dialkyl esters (alkyl=ethyl, n-propyl, n-butyl and n-pentyl), of (S,S)-ethylenediamine-N,N?-di-2-(4-methyl)pentanoic acid dihydrochloride [(S,S)-H4eddl]Cl2 were reported. The composition of the novel platinum complexes was determined by elemental analysis and characterizations were performed by infrared, ¹H and ¹³C NMR spectroscopy. DFT calculations indicate formation one (R,R) from three possible diastereoisomers (S,S; R,S). Complexes 1–4 displayed potent anticancer activity. IC50 values range from 0.74 to 70?M, against tested cell lines, except for CLL cells. The antitumoral activity of 2–4 was found to be considerably stronger to Jurkat and K562. Cell cycle analysis of cell lines showed G1 arrest in the presence of analyzed complexes.

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Posted on 28 May 2012 | 12:58 pm

Prelim iii Editorial board

Publication year: 2012
Source:Inorganica Chimica Acta, Volume 388

Posted on 28 May 2012 | 12:58 pm