# 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.

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## Transition Metal Chemistry - Abstracts

A molybdenum(VI) Schiff base complex immobilized on functionalized Fe 3 O 4 nanoparticles as a recoverable nanocatalyst for synthesis of 2-amino-4 H -benzo[ h ]chromenes

### Abstract

A dioxomolybdenum(VI) complex of a Schiff base, immobilized on the surface of modified Fe3O4 with a silica coating, has been synthesized and characterized by spectroscopic and microscopic techniques including FTIR, TGA, ICP, SEM, EDX, VSM, and XRD analyses. The catalytic performance of this material has been evaluated for the preparation of 2-amino-4H-benzo[h]chromenes via the one-pot, three-component reaction of aldehydes, malononitrile, and 1-naphthol under solvent-free conditions. The benefits of this protocol are short reaction time, simple workup procedure, and high yields of products. Also, the synthesized nanocatalyst could be separated easily from the reaction mixture using an external magnet and reused for four consecutive times with only minor degradation of its catalytic performance.

Datum: 01.03.2018

Syntheses, structures and catalytic activities of molybdenum carbonyl complexes based on pyridine-imine ligands

### Abstract

Thermal treatment of pyridine imines [C5H4N-2-C(H)=N-C6H4-R] [R = H (1), CH3 (2), OMe (3), CF3 (4), Cl (5), Br (6)] with Mo(CO)6 in refluxing toluene provided six novel mononuclear molybdenum carbonyl complexes of the type [(η2-2-C5H4N)CH=N(C6H4-4-R)]Mo(CO)4 [R = H (7); CH3 (8); OMe (9); CF3 (10); Cl (11); Br (12)]. All of these complexes were separated by chromatography and fully characterized by elemental analysis, IR, and NMR spectroscopy. The crystal structures of complexes 7, 8 and 10 were determined by X-ray crystal diffraction analysis. In addition, the catalytic performance of these complexes was also tested, and it was found that these complexes had obvious catalytic activity on Friedel–Crafts reactions of aromatic compounds with a variety of acylation reagents.

Datum: 01.03.2018

Synthesis and characterization of cobalt(II) complexes with triethanolamine and succinate and/or nitrate anions

### Abstract

Three Co(II) complexes of triethanolamine (TEA) namely [Co(N(CH2CH2OH)3)2](NO3)2 (1), [Co(N(CH2CH2OH)3)2](OOC(CH2)2COO) (2) and [Co2(N(CH2CH2OH)3)2(NO3)2(OOC(CH2)2COO)] (3) were synthesized and characterized by physicochemical and spectroscopic methods. The first two complexes are cationic and are formed by Co2+ cations coordinated by two TEA ligands plus nitrate or succinate anions, respectively. The equilibrium geometries of the [Co(TEA)2]2+ cations have been optimized at the B3LYP/cc-pVDZ level. Complex 3 is a product of the reaction between cationic complexes 1 and 2.

Datum: 01.03.2018

Syntheses, structures, and solid-state phosphorescence characteristics of trans -bis(salicylaldiminato)Pt(II) complexes bearing perpendicular N -aryl functionalities

### Abstract

The syntheses, structures, and solid-state emission characteristics of trans-bis(salicylaldiminato)Pt(II) complexes bearing N-aromatic functionalities are described herein. A series of Pt complexes bearing various N-phenyl (1) and N-(1-naphthyl) (2) groups on the salicylaldiminato ligands were prepared by reacting PtCl2(CH3CN)2 with the corresponding N-salicylidene aromatic amines, and the trans-coordination and crystal packing of these complexes were unequivocally established based on X-ray diffraction (XRD). Complexes with 2,6-dimethylphenyl (1c), 2,6-diisopropylphenyl (1d), 1-naphthyl (2a), and 1-(2-methylnaphthyl) (2b) groups on the N atoms exhibited intense phosphorescent emission at ambient temperature in the crystalline state, while those with phenyl (1a), 2,6-dibromophenyl (1b), and 2,6-bis(N,N-dimethylamino)phenyl (1e) functionalities were either less emissive or non-emissive under the same conditions. XRD analyses identified significant intramolecular interactions between Pt and H atoms of the N-aryl functionalities in the emissive crystals of 1c, 1d, and 2a. These interactions were evidently an important factor associated with intense emission at ambient temperature.

Datum: 01.03.2018

DNA binding, antibacterial and antifungal activities of copper(II) complexes with some S-alkenyl derivatives of thiosalicylic acid

### Abstract

The biological activities of two binuclear copper(II) complexes containing S-alkenyl derivatives of thiosalicylic acid are reported [alkenyl = propenyl (L1), isobutenyl (L2)]. The structure of the complex with the S-isobutenyl derivative (C2) was confirmed by single-crystal X-ray structure analysis, which revealed that the structure consists of centrosymmetric, dinuclear complex molecules [Cu2(S-i-butenyl-thiosal)4(DMSO)2] containing two Cu(II) centers bridged by four S-isobutyl-thiosalicylate ligands in a paddle-wheel type structure. The Cu(II) atom is situated in a distorted square-pyramidal environment formed by carboxylate oxygen atoms in the basal plane and a DMSO ligand in the axial position. The reactivities of the complexes toward guanosine-5′-monophosphate (5′-GMP) were investigated. Complex C2 ([Cu2(S-i-butenyl-thiosal)4(H2O)2]) reacted more rapidly with 5′-GMP than complex C1. The interactions of complexes C1 and C2 with calf thymus DNA (CT-DNA) were examined by absorption (UV–Vis) and emission spectral studies (ethidium bromide displacement studies), revealing good DNA interaction abilities. The antimicrobial activities of the free ligands and their complexes were tested by microdilution method, and both minimal inhibitory and microbicidal concentrations were determined. All the tested substances demonstrated selective and moderate antibacterial activity on gram-positive bacteria, but low antibacterial activity on gram-negative bacteria. Also, the tested substances demonstrated low antifungal activity.

Datum: 01.03.2018

Syntheses, structures and properties of a series of nickel(II) complexes derived from amino-5-mercapto-1,3,4-thiadiazole

### Abstract

Four complexes possessing photocatalytic activity, namely [Ni(AMT)2(EDA)2]2 (1), [Ni4(AMT)63-OH)2(H2O)6] (2), [Ni4(AMT)63-OH)2(H2O)6]·4H2O (3) and [Ni4(AMT)63-OH)2(H2O)6]·2H2O (4) (AMT = amino-5-mercapto-1,3,4-thiadiazole and EDA = diethanolamine) have been obtained from solvothermal reactions and characterized by physico-chemical and spectroscopic methods. Although complexes 14 were prepared from common reactants (nickel nitrate and AMT), the use of different organic amines and reaction conditions lead to the observed differences in their structures. Complex 1 is mononuclear, while complex 2 is a {Ni4} cluster. Complexes 34 are expanded into supramolecular structures by hydrogen bonding interactions, but differences in their lattice water molecules lead to the different supramolecular structures. Photocatalytic studies reveal that complex 4 exhibits good catalytic activity for the degradation of the organic dye methylene blue.

### Graphical Abstract

Four complexes possessing photocatalytic activity and constructed from the late transition metal Ni(II) and the 2-amino-5-mercapto-1,3,4-thiadiazole ligand have been obtained in solvothermal conditions. Although complexes 14 were prepared from common reactants (nickel nitrate and AMT), the use of different organic amines and reaction conditions lead to the observed differences in their structures. Complex 1 is mononuclear, while complex 2 is a {Ni4} cluster. Complexes 34 are expanded into supramolecular structures by hydrogen bonding interactions, but differences in their lattice water molecules lead to the different supramolecular structures. Photocatalytic studies reveal that complex 4 exhibits good catalytic activity for the degradation of the organic dye methylene blue.

Datum: 01.03.2018

A comparative study on in vitro cytotoxicity, cellular uptake, localization and apoptosis-inducing mechanism of two ruthenium(II) complexes

### Abstract

Two ruthenium complexes [Ru(MeIm)4(bpy)]2+ (Ru1, MeIm = 1-methylimidazole, bpy = 2,2′-bipyridine) and [Ru(Im)4(bpy)]2+ (Ru2, Im = imidazole) with the same PF 6 counter-ion but different lipophilicities were synthesized and characterized and as potent anticancer agents. The relationships between cellular uptake, localization and molecular action mechanisms of these complexes were elucidated. The results showed that Ru1 with higher logPo/w exhibited faster cellular uptake rates, but lower anticancer activity than Ru2. In addition, Ru1 predominantly accumulated in the mitochondria and cytoplasm, and induced G0/G1 cell cycle arrest, whereas the more hydrophilic Ru2 tended to localize and accumulate in the cell nucleus and mitochondria. Further mechanism studies indicated that Ru2 caused cell cycle arrest at S phase by regulating cell cycle related proteins and induced apoptosis in A549 cells through DNA damage, cellular ROS accumulation, activation of the caspase pathway and mitochondrial dysfunction.

Datum: 01.03.2018

A multi-functional 3D polymolybdate-based copper(II) complex based on an asymmetric pyridyl-amide ligand: synthesis, structure and properties

### Abstract

A polymolybdate-based metal–organic compound {H2[Cu2(L)2(Mo8O27)(H2O)4]} (1) [L = N-(pyridin-3-yl)isonicotinamide] has been synthesized under solvothermal (methanol–water mixed solvent) conditions and structurally characterized by single-crystal X-ray diffraction. Compound 1 exhibits a 3D metal–organic network containing unusual 1D [Mo8O27] n 6n inorganic chains, with adjacent 1D chains connected by Cu(II) atoms and L ligands to form a 3D framework with a trinodal 4,4,6-connected {42.63.8}2{44.68.83} topology. The electrocatalytic activities of compound 1 and its photocatalytic properties for the degradation of organic dyes have also been investigated.

Datum: 01.03.2018

Oxovanadium phenanthroimidazole derivatives: synthesis, DNA binding and antitumor activities

### Abstract

Four unsymmetrical oxovanadium phenanthroimidazole complexes, [VO(hntdtsc)(NPIP)] (1), [VO(hntdtsc)(CPIP)] (2), [VO(hntdtsc)(MEPIP)] (3) and [VO(hntdtsc)(HPIP)] (4) (hntdtsc = 2-hydroxy-1-naphthaldehyde thiosemicarbazone, NPIP = 2-(4-nitrophenyl)-imidazo[4,5-f]1,10-phenanthroline, CPIP = 2-(4-chlorphenyl)-imidazo[4,5-f]1,10-phenanthroline), MEPIP = 2-(4-methylphenyl)-imidazo[4,5-f]1,10-phenanthroline), HPIP = 2-(4-hydroxylphenyl)-imidazo[4,5-f] 1,10-phenanthroline), have been synthesized and characterized. Their DNA binding and antitumor activities were determined by biochemical methods. All four oxovanadium complexes can bind with CT-DNA by an intercalation model and can also cleave supercoiled plasmid DNA in the presence of H2O2. The antitumor properties and mechanism of the complexes have been analyzed by MTT assay, cell cycle analysis, apoptosis assay and Western blot analysis. The results showed that the free ligands and their corresponding complexes all possess antiproliferative activities with very low IC50 values against Hela, BIU-87 and SPC-A-1 cell lines. Complex 1, which has a strongly electron-withdrawing nitro group, exhibited the best antiproliferative activities. Complex 1 caused G0/G1 phase arrest of the cell cycle and induced apoptosis in Hela cells. Additionally, complex 1 attenuated the phosphorylation of extracellular signal-regulated kinases 1 and 2 (ERK1/2).This indicates that inhibition of the ERK1/2 signaling pathway may contribute to the antitumor effects of these complexes.

Datum: 01.03.2018

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: 20.02.2018

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-C5Me t 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: 17.02.2018

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: 16.02.2018

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: 14.02.2018

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: 12.02.2018

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: 10.02.2018

Dye-sensitized solar cell performance of a cobalt(III/II) redox mediator with the 4,5-diazafluoren-9-one ligand

### Abstract

The development of redox shuttles containing electrolytes is very important for obtaining efficient dye-sensitized solar cells (DSSCs). We have therefore synthesized and characterized homoleptic [Co(dafo)3]3+/2+ complexes (dafo = 4,5-diazafluoren-9-one) and studied the effect of the redox diffusion coefficient on the photovoltaic performance of their DSSCs. The compounds were characterized by FTIR, UV–Vis spectroscopy, NMR and MS spectroscopic data. The [Co(dafo)3]2+/3+ system has been used to formulate redox-mediator electrolytes for application in DSSC devices with the N719 ruthenium-polypyridyl dye, TiO2 and CdS sensitizer. This system shows a slightly higher power-conversion efficiency (η = 0.30%) in a DSSC device prepared with a CdS/Pt electrode. Although the [Co(dafo)3]3+/2+ electrolyte shows a moderately high open-circuit potential (Voc = 0.58), it suffers from a reduced short-circuit current (Jcs = 2.04). The data suggest a decreased turnover of the CoIII/II redox couple at the Pt counter electrode for the [Co(dafo)3]3+/2+ system, concomitant with an increased resistance to mass-transfer diffusion.

### Graphical Abstract

Datum: 10.02.2018

Synthesis, crystal structures and biological activities of transition metal complexes of a salen-type ligand

### Abstract

Manganese(III), cobalt(II), nickel(II) and copper(II) complexes of a salen-type ligand, namely 6,6′-((1E,1′E)-(ethane-1,2-diylbis(azanylylidene))bis(methanylylidene))bis(5-isopropyl-2-methylphenol) (H2L), have been synthesized and characterized by physicochemical and spectroscopic methods. In addition, single-crystal X-ray analysis confirmed the formulae of the manganese and nickel complexes as [Mn(OAc)(L)] and [Ni(L)], respectively. The free Schiff base and its complexes have been screened for in vitro antibacterial activity by colony count methods, and the antioxidant activity was assayed by DPPH radical scavenging. The ability of free H2L and its complexes to mediate DNA cleavage was studied by agarose gel electrophoresis.

### Graphical Abstract

Datum: 01.02.2018

Transition metal complexes of a hydrazone derived from hydralazine hydrochloride and 3,5-di-tert-butylsalicylaldehyde

### Abstract

Mononuclear Co(III), Ni(II) and Cu(II) coordination compounds of (E)-1-(3,5-di-tert-butyl-2-hydroxybenzylidene)-2-(phthalazin-1-yl)hydrazine (LH) were prepared and characterized by physicochemical and spectroscopic methods. The metal-to-ligand ratio was found to be 1:2 in [Co(L)2]Cl·2H2O (1) and [Ni(L)2]·2H2O (2), while it is 1:1 in [Cu(L)Cl]·2CH3OH (3). The X-ray crystal structures of LH and complex 1 is are reported. LH shows monobasic behavior, coordinating through NNO donor atoms. The complexes were investigated for their antimicrobial properties. Complexes 1 and 3 show excellent antibacterial and antifungal activities, respectively.

Datum: 01.02.2018

On the kinetics and mechanism of the conversion of Cr(CO) 5 (κ 1 - P -dppm) to Cr(CO) 4 (κ 2 - P , P ′-dppm) (dppm = 1,2-diphenylphosphinomethane): an alternative hypothesis

### Abstract

The data from a previously reported kinetic evaluation dealing with the conversion of Cr(CO)51-P-dppm) (1: dppm = 1,2-diphenylphosphinomethane) into the corresponding chelated complex Cr(CO)42-P,P′-dppm) (2), via CO loss, is re-evaluated. The conclusion is that the process is more likely to involve a rate-determining step that is first-order in [Cr(CO)51-P-dppm)], as opposed to the previously reported zero-order model as proposed. This implies CO loss from 1, by presumably either an I d or more likely a Dissociative (D: S N 1-type) mechanism, leads to 2. This hypothesis is compared and contrasted to reported data and comparisons are made to similar processes involving related Group VI metal carbonyl species.

### Graphical Abstract

$$\mathop {{\text{Cr}}\left( {\text{CO}} \right)_{5} (\upkappa^{1} -P-dppm) + \Delta }\limits_{{\mathbf{1}}} \to \mathop {{\text{Cr}}\left( {\text{CO}} \right)_{4} (\upkappa^{2} -P,P^{{\prime }} {\text{-dppm}}) + {\text{CO}}}\limits_{{\mathbf{2}}}$$

Datum: 01.02.2018

One-dimensional cyanide-bridged Cr(III)–Cu(II) complexes: synthesis, crystal structures and magnetic properties

### Abstract

Using two trans-dicyanidechromium(III) precursors K[Cr(bpdmb)(CN)2] (bpdmb2− = 1,2-bis(pyridine-2-carboxamido)-4,5-dimethyl-benzenate), K[Cr(bpClb)-(CN)2] (bpClb2− = 1,2-bis(pyridine-2-carboxamido)-4-chloro-benzenate) and one Cu(II) complex of a 14-membered macrocycle as ancillary organic ligand as assembling segments, two one-dimensional cyanide-bridged CrIII–CuII complexes {{[Cu(cyclam)][Cr(bpdmb)(CN)2]}ClO4} n ·nCH3OH·nH2O (1) and {{[Cu(cyclam)][Cr(bpClb)(CN)2]}ClO4} n ·nCH3OH (2) (cyclam = 1,4,8,11-tetraazacyclotetradecane) have been synthesized and characterized by elemental analysis, IR spectroscopy and X-ray structure determination. Single X-ray diffraction analysis shows that their similar one-dimensional cationic single-chain structures consist of alternating units of [Cu(cyclam)]2+ and [Cr(bpdmb)(CN)2]/[Cr(bpClb)(CN)2] with free ClO4 as balancing anions. Investigations of the temperature dependences of magnetic susceptibility and the field-dependent magnetization reveal that both complexes have overall ferromagnetic coupling between the neighboring Cr(III) and Cu(II) centers through the bridging cyanide groups.

Datum: 01.02.2018

Category: Current Chemistry Research

Last update: 04.01.2018.