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Transition Metal Chemistry

Current research reports and chronological list of recent articles..




Transition Metal Chemistry is an international scientific journal dealing with all aspects of the preparation of transition metal-based compounds of all kinds, their structural, physical, kinetic and biological properties, their use in chemical synthesis as well as their application in the widest context, their role in naturally occurring systems and more.

The publisher is Springer. The copyright and publishing rights of specialized products listed below are in this publishing house. This is also responsible for the content shown.

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Additional research articles see Current Chemistry Research Articles:

 - Organometallics.



Transition Metal Chemistry - Abstracts



Tuning the regioselectivity of (benzimidazolylmethyl)amine palladium(II) complexes in the methoxycarbonylation of hexenes and octenes

Abstract

Reactions of N-(1H-benzoimidazol-2-ylmethyl-2-methoxy)aniline (L1) and N-(1H-benzoimidazol-2-ylmethyl-2-bromo)aniline (L2) with p-TsOH, Pd(AOc)2 and two equivalents of PPh3 or PCy3 produced the corresponding palladium complexes, [Pd(L1)(OTs)(PPh3)] (1), [Pd(L2)(OTs)(PPh3)] (2) and [Pd(L1)(OTs)(PCy3)] (3), respectively, in good yields. The new palladium complexes 13 and the previously reported complexes [Pd(L1)ClMe] (4) and [Pd(L2)ClMe] (5) gave active catalysts in the methoxycarbonylation of terminal and internal olefins to produce branched and linear esters. The effects of complex structure, nature of phosphine derivative, acid promoter and alkene substrate on the catalytic activities and selectivity have been studied and are herein reported.


Datum: 01.05.2018


A green synthesis of biaryls in water catalyzed by palladium nanoparticles immobilized on N -amidinoglycine-functionalized iron oxide nanoparticles

Abstract

Fe3O4 nanoparticles were prepared by co-precipitation and coated with SiO2 following the Stöber process. N-Amidinoglycine amino acid was then covalently connected to provide an excellent ligand for the immobilization of Pd nanoparticles. The resulting material was characterized by FE-SEM, TEM, EDX, XRD, VSM and ICP-AES analysis. The Fe3O4@SiO2@N-amidinoglycine@Pd0 proved to be a highly active catalyst for the Suzuki coupling reactions of various aryl halides with substituted phenylboronic acids in water, giving the desired products in excellent yields for short reaction times. Moreover, this catalyst can be easily recovered by using an external magnet and directly reused for several times without significant loss of activity.


Datum: 01.05.2018


Kinetics and mechanism of interactions of some monofunctional Au(III) complexes with sulphur nucleophiles

Abstract

Kinetics of the substitution reactions between monofunctional Au(III) complexes, [Au(dien)Cl]2+, [Au(bpma)Cl]2+ and [Au(terpy)Cl]2+ (dien = 3-azapentane-1,5-diamine, bpma = di-(2-picolyl) amine, terpy = 2,2′;6′,2″-terpyridine), and biologically relevant sulphur ligands, namely glutathione (GSH), l-methionine (l-Met) and l-cysteine (l-Cys), were studied in 0.1 M HCl (pH = 1.0). The reactions were followed under pseudo-first-order conditions as a function of ligand concentration and temperature using stopped-flow spectrophotometry. The [Au(terpy)Cl]2+ complex proved to be more reactive than the [Au(bpma)Cl]2+ and [Au(dien)Cl]2+ complexes. The reactivities of the nucleophiles follow the same order for all three complexes, viz. l-Met > GSH > l-Cys. Values of the activation parameters of the reactions support an associative substitution mechanism. In order to confirm that these monofunctional Au(III) complexes undergo a single substitution process in strongly acidic medium, the reaction between [Au(terpy)Cl]2+ and l-Met was studied by HPLC. At pH = 1.0, only one reaction product was detected.


Datum: 01.05.2018


Organophosphines in PtPCOX (X = N, Cl, S), PtPCNX (X = Cl, S, Br, I, As) and PtPCClX (X = S, I, As) derivatives: structural aspects

Abstract

In this review are classified and analyzed structural parameters of almost 90 monomeric organoplatinum complexes with inner coordination spheres consisting of PtPCOX (X = N, Cl, S), PtPCNX (X = Cl, S, Br, I, As) and PtPCClX (X = S, I, As). These complexes crystallized in three crystal systems: orthorhombic (× 11), triclinic (× 32) and monoclinic (× 45). Distorted square planar arrangements about the Pt(II) atoms are provided by mono-, heterobi- and heterotridentate donor ligands. The chelating ligands create a wide variety of four-, five- and six-membered metallocyclic rings and the effects of both steric and electronic factors influence the L–Pt–L bite angles. There are wide variations in the trans-positions of the donor ligands. Two examples are classified as distortion isomers.


Datum: 01.05.2018


Preparation, characterization and crystal structures of metal(II) tetraza macrocyclic complexes with organic co-ligands

Abstract

The complexes [Ni(L1)(pyc)2]·2H2O (1) (L1 = C-meso-5,5,7,12,12,14-hexamethyl-1,4,8,11-tetraazacyclotetradecane; Hpyc = pyrazinecarboxylic acid) and [Cu(L2)(H-cpdc)] (2) (L2 = 3,14-dimethyl-2,6,13,17-tetraazatricyclo[14,4,01.18,07.12]docosane; H2-cpdc = cyclopropanedicarboxylic acid) have been synthesized and structurally characterized. The crystal structure of complex 1 shows a distorted octahedral coordination geometry around the nickel(II) center, with four secondary amines in the equatorial positions and two nitrogen atoms of the pyc ligands in the trans positions. In complex 2, the coordination environment around the copper(II) center is a Jahn–Teller distorted octahedron with four Cu–N bonds and two axial Cu–O bonds. The electronic spectra, electrochemical and TGA behavior of the complexes are significantly affected by the nature of the axial pyc and H-cpdc ligands.


Datum: 01.05.2018


Dinuclear NHC–palladium(II) complexes: synthesis,characterization and application to Suzuki–Miyaura cross-coupling reactions

Abstract

Four dinuclear N-heterocyclic carbene–palladium(II) complexes 14 were prepared and characterized by elemental analysis and spectroscopic methods. The X-ray crystal structure of complex 2 showed a dinuclear framework in which N-heterocyclic ligands bridge between two square planar palladium(II) units. Each palladium center is surrounded by an imidazolylidene, a nitrogen atom from the central linking ligand, and two trans-chloride ligands. These dinuclear NHC–palladium(II) complexes exhibited efficient catalytic activities for the Suzuki–Miyaura coupling of aryl and benzyl chlorides with arylboronic acids.

Graphical Abstract


Datum: 01.05.2018


Syntheses, structures, and catalytic activity in Friedel–Crafts acylations of substituted tetramethylcyclopentadienyl molybdenum carbonyl complexes

Abstract

Reactions of the substituted tetramethylcyclopentadienes [C5HMe4R] [R = t Bu, Ph, CH2CH2C(CH3)3] with Mo(CO)3(CH3CN)3 in refluxing xylene gave a series of dinuclear molybdenum carbonyl complexes [(η5-C5Me4R)Mo(CO)3]2 [R = t Bu (1), Ph (2), CH2CH2C(CH3)3 (3)], [(η5-C5Met Bu)Mo(μ-CO)2]2 (4)], and [(η5-C5Me4)t Bu]2Mo2O4(μ-O) (5)], respectively. Complexes 15 were characterized by elemental analysis, IR, 1H NMR, and 13C NMR spectroscopy. In addition, their crystal structures were determined by X-ray crystal diffraction analysis. The catalytic activities of complexes 13 in Friedel–Crafts acylation in the presence of o-chloranil has also been investigated; the reactions were achieved under mild conditions to give the corresponding products in moderate yields.


Datum: 01.05.2018


Nitrile functionalized silver(I) N -heterocyclic carbene complexes: DFT calculations and antitumor studies

Abstract

A series of aliphatic nitrile functionalized benzimidazolium salts and their respective mononuclear N-heterocyclic carbene Ag(I)-NHC complexes are reported. The benzimidazolium salts were synthesized by N-alkylation of 1H-benzimidazole with an appropriate alkyl bromide, followed by reaction with either 5-bromovaleronitrile or 6-bromohexanenitrile. The respective mononuclear Ag(I)-NHC complexes were prepared by the reaction of the benzimidazolium salts with Ag2O. All the synthesized compounds were characterized by physico-chemical and spectroscopic techniques. The molecular structures of the two complexes were elucidated through single-crystal X-ray diffraction analyses. Density functional theory was used to model the structures of the other complexes. The benzimidazolium salts and their complexes were screened for cytotoxicity against a breast cancer cell line (MCF-7), using the MTT assay. All the Ag(I)-NHC complexes gave IC50 values ranging from 7.0 ± 1.06 to 12.9 ± 1.55 µM which are comparable to the standard drug, tamoxifen (IC50 = 11.2 ± 1.84 µM), while all of the benzimidazolium salts proved to be inactive.


Datum: 01.05.2018


Complexation of hydroxamate-based siderophores with cobalt(II/III): growth inhibitory effect of cobalt(III)-desferricoprogen complex on fungi

Abstract

Solution equilibrium results for Co(II) and Co(III) complexes of two natural hydroxamate-based siderophores, the exocyclic desferricrocin (DFR) and the endocyclic triacetylfusarinine (TAF) are presented. The three hydroxamate chelating functions of TAF were found to complete the octahedral coordination sphere of a Co(II) ion in stepwise processes, but following the coordination of two hydroxamates of DFR practically in one step, the third function, most probably because of sterical reasons, remained uncoordinated. A comparison with corresponding results for the previously studied acyclic desferrioxamine B (DFB) and desferricoprogen (DFC) provided some information about the effects of the molecular framework of siderophores on their cobalt-binding ability. The oxidation of the central metal ion under basic conditions and investigation of the cobalt(III) complexes by cyclic voltammetry were also made. Compared to Fe(III), by several orders of magnitude, higher stability complexes were formed with Co(III). The possibility of any effect of the Co(III)-siderophore complex on microbial Fe(III) uptake was tested by investigation of the antifungal effect of Co(III)-DFC in comparison with that of CoCl2 on two fungi cultures, Penicillium brevicompactum and Aspergillus fumigatus.


Datum: 01.05.2018


Crystal structures and spectroscopic properties of copper(II)–dipicolinate complexes with benzimidazole ligands

Abstract

The syntheses, crystal structures and spectroscopic properties of three Cu(II)–dipicolinate complexes with benzimidazole ligands, namely [Cu(bzim)(dipic)(MeOH)] (1), [Cu2(2-Etbzim)2(dipic)2]n ·0.5nH2O (2) and [Cu2(2-iPrbzim)2(dipic)2]n (3), where dipic = dipicolinate, bzim = 1-H-benzimidazole, 2-Etbzim = 2-ethyl-1-H-benzimidazole and 2-iPrbzim = 2-isopropyl-1-H-benzimidazole, are reported. Crystal structure studies revealed different coordination modes of the dipicolinate ligands; tridentate chelating for monomeric complex 1, and both tridentate chelating and bridging for similar polymeric complexes 2 and 3. Polymers 2 and 3 both contain two units, in which the Cu(II) central atoms Cu1 and Cu2 have different coordination polyhedra. The first unit {Cu(dipic)2} with Cu1 is connected to the second via two bidentate carboxylate groups of an μ3-bridging dipicolinate. In the second unit, Cu2 is coordinated by two imidazole nitrogen atoms from 2-ethyl-1-H-benzimidazole (2) or 2-isopropyl-1-H-benzimidazole (3) ligands. Complex 2 is of higher symmetry and has a localized Cu(II) atom Cu2 in a special position on the twofold axis. EPR spectra of all three Cu(II) complexes, which were measured at both room temperature and 98 K, indicate distorted tetragonal coordination spheres for all the Cu(II) atoms. The g-factor relation (g//> g > 2.0023) is consistent with a \(d_{{x^{2} - y^{2} }}\) ground electronic state in each case.


Datum: 24.04.2018


Syntheses, steric hindrance effects, luminescent properties and TD-DFT calculations for a series of copper(I) iodide coordination complexes

Abstract

A series of copper(I) coordination complexes, CuI(Phen)[2-(Dpp)bp] (1) (Phen = phenanthroline, 2-(Dpp)bp = 2-(Diphenylphosphino)-biphenyl), Cu2I2(Phen)[2-(Dpp)bp] (2), CuI(2-PBI)[2-(Dpp)bp] (3) and (2-PBI = 2-(pyridin-2-yl)-1H-benzo[d]imidazole) and CuI(Bipy)[2-(Dpp)bp] (Bipy = 2,2′-bipyridine) (4) have been synthesized. X-ray crystal structure studies revealed that complexes 1, 3 and 4 showed mononuclear structures with the copper atoms coordinated by iodide, a chelating nitrogen-donor ligand, and a monodentate phosphine ligand. However, the coordination centers display different distortions of their tetrahedral geometries, according to the steric hindrance of the bulky phosphine ligands. Complex 2 has a dinuclear structure, with trigonal and tetrahedral coordination centers. Variations in the aromatic system of the N-heterocyclic ligands result in different luminescence properties. Thus, the emission maxima for these complexes range from 580 to 642 nm, with lifetimes of τ = 0.6–0.9 and 1.6–4.2 μs. TD-DFT calculations reveal the origin of the luminescence to be metal–ligand charge transfer, as well as halogen–ligand charge transfer. The optical absorption spectra and thermal stabilities of the complexes have also been studied.


Datum: 20.04.2018


Three coordination polymers constructed from succinic acid and 1,4-bis(1H-imidazol-4-yl)benzene: synthesis, crystal structures, and properties

Abstract

Three coordination polymers involving transition metals, namely [Co(suc)(1,4-bib)(H2O)2]n (1), [Mn(suc)(1,4-bib)(H2O)2]n (2), [Cd(suc)(1,4-bib)]n (3) (H2suc = succinic acid, 1,4-bib = 1,4-bis(1H-imidazol-4-yl)benzene), have been synthesized under solvothermal conditions. All three compounds were characterized by single-crystal X-ray diffraction, elemental analysis, FTIR, UV–Vis spectroscopy, powder X-ray diffraction and thermogravimetric analyses. Compounds 1 and 2 show 2D metal–organic layers with the point symbol of {44·62}. The 3D framework of compound 3 displays a 4-connected dia net with the point symbol of {66} topology. Magnetic susceptibility studies of compound 1 indicate weak antiferromagnetic coupling between the Co(II) centers. The adsorption experiment results show that compound 3 exhibits rapid and selective separation of congo red over methylene blue and rhodamine B.


Datum: 18.04.2018


Enantiomeric pairs of copper(II) polypyridyl-alanine complex salts: anticancer studies

Abstract

The anticancer properties of two previously characterized pairs of optically pure chiral complex salts [Cu(phen)(ala)(H2O)]X·xH2O (phen = 1.10-phenanthroline; X = NO3; ala: l-alanine (l-ala) 1 and d-alanine (d-ala) 2; and (X = Cl; ala: l-ala, 3 and d-ala, 4; x = number of lattice water molecules) are reported herein, together with the crystal structure of the d-enantiomer 4. Unlike cisplatin which is ineffective against MCF-7 cancer cells with the absence of caspase-3 protein expression, these two pairs of complex salts were effective against this cell line and they were able to induce an increase in intracellular ROS, loss in mitochondrial membrane potential, cell cycle arrest mainly at SubG1 phase , caspase-9 activation, and caspase-3/caspase-7-independent apoptosis. Screening of 1 on the NCI-60 panel of human cancer cell lines showed that it was effective against most of the cell lines. MTT-NCI modified assay screening was also done on other cancer cell lines, viz. A549, CNE1, and HepG2, and two normal cell lines, viz. MCF-10A and CHANG. The effects of chirality of these Cu(II) compounds, especially the greater selectivity of d-enantiomers over the l-counterparts, on their anticancer properties are also reported herein.


Datum: 17.04.2018


Organometallic polymer-functionalized Fe 3 O 4 nanoparticles as a highly efficient and eco-friendly nanocatalyst for C–C bond formation

Abstract

A magnetically recoverable biopolymer-based nanocatalyst was prepared through the covalent immobilization of a chitosan-bound 2-hydroxynaphthaldehyde Pd complex on the surface of superparamagnetic nanoparticles. The nanocatalyst was characterized by FTIR, X-ray powder diffraction and scanning electron microscopy, revealing an average particle size of 70 nm. The catalyst shows high thermostability by thermogravimetric analysis. Estimated Pd loading by inductively coupled plasma atomic emission analysis was found to be 0.348 mmol g−1. The nanocatalyst exhibits excellent catalytic performance in Suzuki couplings of various aryl halides with phenylboronic acid, and Heck reactions of iodo- and bromoarenes with butylacrylate. The catalyst can be easily separated from the reaction mixture with an external magnet and reused consecutively four times without significant loss in activity.


Datum: 12.04.2018


Synthesis, structure, magnetic and catalytic behavior of a dinuclear copper(II) complex with triazendio ligands

Abstract

A dinuclear copper(II) complex [Cu2L4] has been prepared by the reaction of CuCl2·2H2O and 1-[(2-iodo)benzene]-3-[benzothiazole] triazene (HL). The complex has been characterized by X-ray crystallography and by physico-chemical and spectroscopic methods. In the solid state, there is a significant antiferromagnetic coupling between the copper(II) centers with a coupling constant (J) of − 558 cm−1. In homogeneous solution, the complex shows electrocatalytic activities for hydrogen generation from both acetic acid and neutral buffer with a turnover frequency of 50 mol of H2 per mole of catalyst per hour (mol H2/mol catalyst/h) at an overpotential (OP) of 941.6 mV, and 502 mol H2/mol catalyst/h at an OP of 836.7 mV.


Datum: 04.04.2018


Correction to: 3-Aminoquinazolinone–phosphine ligands and their ruthenium(II) complexes: application in catalytic hydrogenation and transfer hydrogenation reactions

Abstract

In the initial online publication, there was a mistake in the title. The first words read “3-Aminoquinazolinone–phosphine” instead of “3-Aminoquinazolinone–phosphine”. The original article has been corrected.


Datum: 01.04.2018


Magnetic nanoparticles coated with a chitosan anchored Schiff base complex of nickel(II) as an effective, reusable catalyst for one-pot synthesis of spirolactones

Abstract

A simple, highly versatile and efficient synthesis of spirolactones is achieved through the three components, one-pot reaction of 5-chloroisatin, different primary amines, and dimethyl acetylenedicarboxylate, using Fe3O4@CS-Schiff base Ni as a highly efficient heterogeneous catalyst. The catalyst can be recovered for subsequent reactions and reused for at least five rounds without any appreciable loss of activity. The core–shell structure and the composition of the magnetic nanocatalyst were characterized by physical and spectroscopic techniques.

Graphical Abstract


Datum: 01.04.2018


3-Aminoquinazoline–phosphine ligands and their ruthenium(II) complexes: application in catalytic hydrogenation and transfer hydrogenation reactions

Abstract

3-Aminoquinazolinone–phosphine proligands (5ae) and their Ru(II) complexes (6ae) were prepared and characterized by NMR (1H, 13C, 31P{1H}), FTIR and microanalysis. The 3-aminoquinazolinone–phosphine ligands were found to coordinate with the Ru(II) center via their phosphorus and nitrogen atoms. The Ru(II) complexes were applied as catalysts for the hydrogenation and transfer hydrogenation of prochiral ketones. The results showed that these complexes are efficient transfer hydrogenation catalysts.


Datum: 01.04.2018


Assembly, characterization and dye adsorption properties of two transition metal coordination polymers constructed from a flexible bis(pyridyl-tetrazole) ligand

Abstract

Two copper(II)/cobalt(II) coordination polymers formulated as [Co(3-bptzp)(1,4-BDC)(1,4-H2BDC)0.5] (1) and [Cu(3-bptzp)(1,4-BDC)] (2) have been hydrothermally synthesized by using a flexible bis(pyridyl-tetrazole) ligand (3-bptzp = 1,4-bis(5-(3-pyridyl)tetrazolyl)propane) and an aromatic dicarboxylic acid (1,4-H2BDC = 1,4-benzenedicarboxylic acid) as mixed ligands. Both complexes have been characterized by single-crystal X-ray diffraction, elemental analyses, infrared spectroscopy and powder X-ray diffraction. There are two different types of 2D layered network in the structures of both complexes. In complex 1, the 2D layered network is formed by 1,4-BDC anions and neutral 1,4-H2BDC ligands, while the 3-bptzp ligands bridge the adjacent two Co(II) atoms to form a [Co2(3-bptzp)2] ring. In complex 2, adjacent Cu(II) atoms are bridged by 1,4-BDC anions to form a 1D [Cu(1,4-BDC)]n chain, and then adjacent 1D [Cu(1,4-BDC)]n chains are further linked together by the 3-bptzp ligands to generate a 2D layered network. The electrochemical behaviors and dye adsorption properties of both complexes have been studied.

Graphical Abstract

Two new coordination polymers constructed from a flexible bis(pyridyl-tetrazole) ligand have been hydrothermally synthesized. There exist two different types of 2D layered structures in the complexes 1 and 2. In addition, the electrochemical behaviors and dye adsorption properties of complexes 1–2 have been studied.


Datum: 01.04.2018


A copper(II) complex of 6-(pyrazin-2-yl)-1,3,5-triazine-2,4-diamine and L-serinate: synthesis, crystal structure, DNA-binding and molecular docking studies

Abstract

A water-soluble Cu(II) complex, [Cu(pzta)(L-Ser)(ClO4)]·1.5H2O (pzta = 6-(pyrazin-2-yl)-1,3,5-triazine-2,4-diamine; L-Ser = L-serinate), was synthesized and characterized by analytical and spectral techniques. In addition, the molecular structure of the complex was confirmed by single-crystal X-ray diffraction, revealing that the central Cu(II) atom was located in a six-coordinate distorted octahedral geometry. Multi-spectroscopic methods, viscosity measurements and thermal denaturation experiments revealed that the complex binds to DNA with apparent binding constant of 2.93 × 103 M−1 through a groove binding mode. The positive values of ΔH and ΔS obtained from isothermal titration calorimetry experiments indicated that hydrophobic interactions play an important role in the formation of the complex–DNA adduct. Molecular docking studies were carried out to better understand the binding mode of the complex with DNA.


Datum: 01.04.2018


 


Category: Current Chemistry Research

Last update: 28.03.2018.






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