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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



Synthesis, structures and properties of copper(II) and zinc(II) complexes with 1,2-bis(benzimidazol-2-yl)ethane ligands

Abstract

1,2-Bis(benzimidazol-2-yl)ethane (bbe) and its transition metal complexes, [Cu(bbe)Cl2]·DMF (1) and [Zn(bbe)Cl2]2(2), have been synthesized and characterized by elemental analysis, UV–Vis and IR spectra. X-ray crystal structure analysis revealed that both complexes have four-coordinate, distorted tetrahedral geometries. Complex 2 has two crystallographically independent but chemically identical Zn(bbe)Cl2 units. The cyclic voltammogram of complex 1 shows an irreversible Cu2+/Cu+ couple. In vitro antioxidant tests showed that complex 1 has significant antioxidant activity against superoxide. Photoluminescence investigations showed that complex 2 exhibits light blue (441 nm) photoluminescence. Compared with the free bbe proligand, a redshift of 16 nm was observed for complex 2, which may be attributed to π*–π transitions.


Datum: 25.06.2019


Synthesis and characterization of diiron ethane-1,2-dithiolate complexes with tricyclohexylphosphine, methyl diphenylphosphinite, or tris(2-thienyl)phosphine coligands

Abstract

We have prepared three diiron ethane-1,2-dithiolate complexes [Fe2(CO)5L(µ-SCH2CH2S)] [L = P(C6H11)3, 2; Ph2POCH3, 3; P(2-C4H3S)3, 4] by CO exchange of the starting complex [Fe2(CO)6(µ-SCH2CH2S)] (1) with the corresponding phosphine ligands tricyclohexylphosphine, methyl diphenylphosphinite, or tris(2-thienyl)phosphine in the presence of Me3NO as an oxidant for CO. The complexes have been characterized by elemental analysis, spectroscopy, and single-crystal X-ray diffraction analysis.


Datum: 21.06.2019


A ruthenium(II) complex with a methylated polypyridine ligand: synthesis, DNA binding, and antiproliferation activity

Abstract

A ruthenium polypyridine complex, [Ru(mptpy)(Mmptpy)Cl][PF6]2 (Ru1, mptpy = 4-(4-methylphenyl)-2,2′,6′,2″-mptpyridine, Mmptpy = 2-[4-(4-methylphenyl)-2,2′-bipyridin-6-yl]-1-methylpyridinum), was synthesised and characterised. The structure of the complex was determined by single-crystal X-ray crystallography. The ruthenium(II) core has an octahedral coordination environment. The interactions of the complex with DNA were analysed by UV–Vis and fluorescence spectroscopy, revealing a high binding affinity for double-stranded DNA. DNA photocleavage studies monitored by agarose gel electrophoresis showed that the complex cleaved DNA efficiently, whilst mechanistic studies showed that the complex produced reactive oxygen species including singlet oxygen, superoxide anions, and carbon-based radicals that cleave DNA. The complex also showed notable antiproliferation activity towards cancer cells in methyl thiazolyl tetrazolium assays.


Datum: 15.06.2019


Correction to: Bis-chelates of nickel(II) and copper(II) with an O,S-donor piperazine ligand

After the publication of this article ‘Bis-chelates of nickel(II) and copper(II) with an O,S-donor piperazine ligand,’ it came to our attention that Debashis Ray was omitted from the list of authorship. Debashis Ray supervised this work at IIT Kharagpur and has been added as an author to this publication. The authors would also like to clarify that this work was carried out at the Department of Chemistry, Indian Institute of Technology (IIT) Kharagpur and this is the affiliation for both authors for this article. During this work, Haridas Mandal was a Ph.D. student at IIT Kharagpur, working under the supervision of Prof. Ray. He has since moved to the Chemical Division, Southern Region, Geological Survey of India, and this is his current affiliation. Dr. Mandal is thankful to the Department of Science and Technology, Govt. of India, New Delhi, for providing the single-crystal X-ray diffractometer in the Department of Chemistry, IIT Kharagpur, under its FIST program.


Datum: 12.06.2019


Studies of the anticancer activities of ruthenium(II) polypyridyl complexes toward human hepatocellular carcinoma BEL-7402 cells

Abstract

Two ruthenium(II) polypyridyl complexes formulated as [Ru(bpy)2(THPDP)](PF6)2 (1) and [Ru(ttbpy)2(THPDP)](PF6)2 (ttbpy = 4,4ʹ-ditertiary butyl-2,2ʹ-bipyridine) (2) were synthesized and characterized by elemental analysis, 1H NMR, 13C NMR and UV–Vis spectra. The cytotoxic activities of the complexes against cancer cell lines BEL-7402, A549, SGC-7901, HeLa and normal NIH3T3 cells were investigated by 3-(4,5-dimethylthiazole)-2,5-diphenyltetrazolium bromide (MTT) methods. The complexes show moderate cytotoxicity toward BEL-7402 and HeLa cells. The changes in mitochondrial membrane potential, intracellular Ca2+ and reactive oxygen species were studied by fluorescence microscopy. Both complexes can increase intracellular Ca2+ concentrations and ROS levels and induce a decrease in mitochondrial membrane potential. They also inhibit cell invasion and suppress cell proliferation at the G0/G1 phase. Additionally, they activate caspase 3, cleave PARP and regulate the expression of Bcl-2 family proteins. In short, the complexes induce apoptosis in BEL-7402 cells through a ROS-mediated mitochondria dysfunction pathway.


Datum: 10.06.2019


Syntheses, crystal structures and photocatalytic properties of transition metal complexes based on 9,10-anthraquinone-1,3-dicarboxylate

Abstract

Five transition metal complexes based on the ligand 9,10-anthraquinone-1,3-dicarboxylate acid (1,3-H2AQDC) have been synthesized and characterized by physico-chemical and spectroscopic methods. Single-crystal analyses show that the complexes {Mn(1,3-AQDC)(H2O)4·(H2O)}n, {Zn(1,3-AQDC)(H2O)4·(H2O)}n, {Ni(1,3-AQDC)(4,4′-bpy)(H2O)2(CH3OH)}n and {Co(1,3-AQDC)(4,4′-bpy)(H2O)2(CH3OH)}n (4,4′-bpy = 4,4′-bipyridine) comprise one-dimensional (1D) chains in their crystal structures, while [Ni(1,3-AQDC)(H2O)4·(H2O)3]2 bears dimeric units, and these secondary building units are further linked by hydrogen bonding to form three-dimensional structures. These compounds proved to be able to catalyze visible-light-driven air-oxidation reactions of diarylethyne into diketones under mild conditions.


Datum: 04.06.2019


Construction and catalytic applications of an amino-functionalized covalent organic framework

Abstract

Functionalization of covalent organic frameworks (COFs) with specific groups will endow them special characteristics, and further complexation with transition metals may improve their catalytic performance and widen their applications. Herein, we constructed an amino-functionalized covalent organic framework TpPa–NH2 by the facile reduction in TpPa–NO2 and took it as a carrier for transition metal ion Cu(II) to yield a hybrid Cu–COF. All characterizations verified that the crystallinity and porosity of original COF were retained after functionalization. Subsequent evaluation of their catalytic performance indicated that the framework TpPa–NH2 has potential application in alkali-catalyzed reactions, while the hybrid Cu–COF displayed satisfactory catalytic performance both in selective oxidation of styrene and the reduction in 4-nitrophenol to 4-aminophenol. The above results demonstrated that TpPa–NH2 is a promising platform with diverse applications, and the introduction of Cu(II) will endow the material with more potential applications in oxidation and reduction reactions.


Datum: 23.05.2019


Preparation of chromium catalysts bearing bispyridylamine and its performance in ethylene oligomerization

Abstract

A series of bispyridylamine ligands and chromium complexes designed for ethylene oligomerization have been synthesized, which was made up of both neutral organic ligand and inorganic anion. The compositions of these complexes have been fully characterized by spectroscopic and analytical methods. Catalysts (Cr1Cr4) were evaluated in detail with methylaluminoxane (MAO) as an activator in the ethylene oligomerization. As a result, Cr1 achieved a higher catalytic activity of 2.93 × 105g/(mol(Cr) h) and a higher selectivity of 55.34% toward the valuable C8 compound using toluene as the solvent. The total selectivity to LAOs was 71.2%.


Datum: 20.05.2019


Polyethyleneimine-stabilized palladium nanoparticles for reduction of 4-nitrophenol

Abstract

Palladium nanoparticles (Pd NPs) have been drawing great interest as catalysts for water treatment. Herein, high molecular weight polyethyleneimine (PEI) (molecular weight: 70 kDa) was used as template to stabilize Pd NPs. PEI was incubated with disodium tetrachloropalladate, followed by reduction with sodium borohydride. Pd NPs had narrow size distribution with diameter from 3.64 to 6.20 nm. The PEI-stabilized palladium nanoparticles (Pdn-PEI NPs) showed excellent long-term stability and positive zeta potential in phosphate saline buffers with different pH values. In addition, Pdn-PEI NPs exhibited high efficiency for catalysis of 4-nitrophenol (4-NP) in aqueous solution. The catalytic reduction of 4-NP followed the pseudo-first-order behavior, which had the highest catalytic ability (knor = 229). The enhanced properties can be attributed to the high stability and smaller size of Pdn-PEI NPs in aqueous solution, resulting from the application of PEI template. This method can be used to prepare highly stable metal nanoparticles with potential applications in catalysis of polluted water in the future.

Graphical abstract


Datum: 15.05.2019


Structurally characterized trinuclear nickel(II) and copper(II) Salamo-type complexes: syntheses, Hirshfeld analyses and fluorescent properties

Abstract

Two trinuclear Ni(II) and Cu(II) coordination compounds [{Ni(L1)(C2H5OH)}2(μ-OAc)2Ni]·2C2H5OH (1) and [{Cu(L2)(CH3OH)}2(μ-OAc)2Cu]·2CH3OH (2) constructed from asymmetrical Salamo-type ligands H2L1 and H2L2 (H2L1 = 5-(N,Nʹ-diethylamino)-2,2ʹ-[ethylenediyldioxybis(nitrilomethylidyne)]diphenol and H2L2 = 2,2ʹ-[ethylenediyldioxybis(nitrilomethylidyne)]naphtholphenol) were synthesized and characterized by physicochemical and spectroscopic methods. Complex 1 is a centrosymmetrical trinuclear Ni(II) coordination compound. Three hexa-coordinated Ni(II) atoms have slightly distorted octahedral geometries. Complex 2 contains three hexa-coordinated Cu(II) atoms bearing distorted octahedral geometries too. In addition, the thermal analyses and Hirshfeld surfaces analyses of complexes 1 and 2 have been discussed in detail.


Datum: 15.05.2019


Structural and chromotropism properties of copper(II) complexes with 3,3′-((pyridin-2-ylmethyl)azanediyl)dipropanamide ligand

Abstract

A tetra-dentate ligand L [3,3′-((pyridin-2-ylmethyl)azanediyl)dipropanamide] was synthesized and characterized by spectroscopic and structural methods. The reaction of L with two different copper(II) halides [CuX2; X = Br, Cl] in a similar condition yielded two different compounds of [LCuCl]Cl, 1 and [CuLBr]2[CuBr4]·CH3OH·H2O, 2. Both compounds were characterized by several physicochemical techniques. Single-crystal X-ray studies revealed that the Cu(II) centers in the cationic complexes 1 and 2 are in a square pyramidal N2O2X (X = Cl and Br) environment. Compound 1 is chromotropic and its solvatochromism and halochromism properties were investigated. It was found that the observed positive solvatochromism is due to structural change and solvation of the vacant site of the complex. The complex demonstrated distinct reversible spectral change over the pH range 1.3–12.1 and can act as pH-induced off–on–off absorption switch through deprotonation and the Cu–O to Cu–N bond rearrangement of the coordinated amide groups in aqueous solution.


Datum: 10.05.2019


Influence of hydrothermal synthesis temperature on the redox and oxygen mobility properties of manganese oxides in the catalytic oxidation of toluene

Abstract

A series of MnOx samples synthesized by hydrothermal methods at different temperatures were investigated as catalysts for the oxidation of toluene. The optimum oxidation performance was achieved with the catalyst prepared at 120 °C (Mn-120), for which complete conversion of toluene was attained at 250 °C. The Mn-120 sample possessed the highest concentration of Mn3+ and the highest initial H2 consumption rate, which are indicative of abundant crystal defects and superior reducibility. In addition, Mn-120 exhibited excellent oxidation ability due to the abundance of lattice oxygen species and excellent oxygen mobility. Therefore, the superior catalytic performance of Mn-120 could be attributed mainly to its redox performance and abundant crystal defects, both of which are determined by the temperature of the hydrothermal synthesis of MnOx.


Datum: 07.05.2019


Crystal structure, Hirshfeld surface analysis and photocatalytic activities of a cobalt(III) complex based on acid and alkaline mixed ligands

Abstract

A novel Co(III) complex [Co(chda)(nta)] (1) (chda = trans-(1R,2R)-1,2-cyclohexanediamine, H3nta = nitrilotriacetic acid) was synthesized based on chda and H3nta ligands at room temperature. Complex 1 was structurally identified by single-crystal X-ray diffraction, elemental analysis, FT-IR and Raman spectrum. Complex 1 was connected by the intermolecular N–H···O hydrogen bonds to form a 2D supramolecular structure. The 3D Hirshfeld surface and 2D fingerprint plots were used to further study the intermolecular interactions of complex 1. The intermolecular O···H and H···H contacts were the most significant interactions in the crystal, which comprised 96.6% of the total Hirshfeld surface. In addition, complex 1 exhibited excellent photocatalytic activity for the removal of methylene blue under UV light. The possible photocatalytic mechanism and reaction kinetics were also discussed.


Datum: 04.05.2019


Effect of ring substitution on synthesis of benzimidazolium salts and their silver(I) complexes: characterization, electrochemical studies and evaluation of anticancer potential

Abstract

A series of bidendate 5,6-dimethyl benzimidazolium-based N-heterocyclic carbene (NHC) proligands and their silver complexes were synthesized. The synthetic approaches to the proligands were constrained by the methyl substituents, which impose a significant impact on the reactivity according to their sigma electron-donating abilities. The corresponding silver(I) complexes were obtained by in situ deprotonation of the NHCs and characterized by physicochemical and spectroscopic methods. In addition, a single-crystal X-ray diffraction study of complex C5 revealed its dinuclear structure. Irreversibility of redox events was observed in electrochemical studies of these complexes. In vitro anticancer studies of the azolium salts and their silver(I) complexes against human breast cancer (MDA-MB-231), colon cancer (HCT-116) and normal endothelial (EA.hy926) cells revealed that all the compounds are more cytotoxic to cancer cells than to normal cells and the complexes are more potent than their corresponding NHC proligands. Increased chain length, the presence of methyl substituents on the benzimidazole ring and aryl linker and two silver centres all enhance the biopotency of these complexes.

Graphical abstract

Substituted benzimidazolium-based N-heterocyclic carbene (NHC) proligands and silver complexes are advantageous anticancer tools for medicinal chemistry.


Datum: 04.05.2019


Three Schiff base complexes based on diethylenetriamine: synthesis, structure, DNA binding and cleavage, and in vitro cytotoxicity

Abstract

Cu(II) and Zn(II) complexes with Schiff bases derived from diethylenetriamine, [Cu(C22H23N5)(H2O)(ClO4)2] (1), [Cu(C14H18N4)(ClO4)](ClO4) (2), and [Zn(C10H17N5Cl)]4[ZnCl4]2·H2O (3), have been synthesized and structurally characterized. The interactions of the complexes with CT-DNA were investigated by electronic absorption, circular dichroism (CD), and fluorescence spectroscopies. All three complexes appear to bind to DNA via groove binding modes. The order of DNA binding strength was 2 > 1 > 3. The complexes proved to be capable of efficient cleavage of pBR322 DNA at micromolar concentrations in the presence of ascorbic acid as a reducing regent. The hydroxyl radical may be the reactive species, and H2O2 may be involved in DNA strand breakage induced by these complexes. Furthermore, in vitro cytotoxicities of the complexes against four human carcinoma cell lines (HepG2, MGC-803, EC9706, and MCF-7) were screened by MTT assays. Complex 2 shows potent activity against HepG2 and MGC-803 cell lines; for all four cell lines, the activities of the complexes follow the order: 2 > 1 > 3. Hence, the different anticancer activities of the complexes may be correlated with their DNA binding abilities.


Datum: 03.05.2019


Cyanide-bridged polynuclear heterobimetallic complexes: synthesis, crystal structures, and magnetic properties

Abstract

The reactions of [MnIII(3-EtOSalen)(H2O)2]ClO4 (Salen=N,N-ethylenebis(salicylideneaminato)dianion) with K3[M(CN)8] (M=Mo, W) have been investigated, from which cyanide-bridged hexanuclear Mo–Mn and binuclear W–Mn complexes formulated as {[Mn(3-EtOSalen)(H2O)]4[Mn(3-EtOSalen)(CH3OH)][MoCN8]}(CN)2·CH3CN·H2O (1) and {[Mn(3-EtOSalen)(H2O)2][Mn(3-EtOSalen)(H2O)(EtOH][MnIII(3-EtOSalen)(H2O) W(CN)8]}·0.5CH3OH (2), respectively, were obtained and characterized by elemental analysis, IR spectroscopy and X-ray crystal structure determination. X-ray diffraction analysis for complex 1 shows that it has a cyanide-bridged cationic hexanuclear Mn5Mo structure in which two free and disordered CN ions from the cyanide precursor are present as balance anions, while the [Mo(CN)8]3− ion acting as a pentadentate ligand connects five Schiff base manganese(III) units. In complex 2, the [W(CN)8]3− ion is coordinated with a single Schiff base manganese unit by one of its cyanide groups, so forming a cyanide-bridged anionic binuclear structure whose dinegative charge is balanced by two free Schiff base manganese cations. Both of these cyanide-bridged complexes can be considered as self-complementary, such that the coordinated aqua ligand from one complex and the O4 compartment from the Schiff base ligand of the neighboring complex form a supramolecular two-dimensional network and a one-dimensional ladder-like double-chain structure, respectively. Investigation of the magnetic properties of these complexes reveals antiferromagnetic interactions within the cyanide-bridged Mn–Mo/W units. The magnetic susceptibilities of both complexes have been modeled.


Datum: 01.05.2019


Three silver coordination polymers constructed from 4,4′-bipyridine-like ligands and 2,5-thiophenedicarboxylic acid: crystal structures and photocatalytic performances

Abstract

Three coordination polymers (CPs), formulated as [Ag(bpy)]2(tdc)·4H2O (BUC-78), [Ag(bpe)]2(tdc)·6H2O (BUC-79) and [Ag(bpp)]2(tdc)·8H2O (BUC-80) have been synthesized from the reactions between AgNO3, 4,4′-bipyridine (bpy),1,2-bis(4-pyridyl)ethylene (bpe),1,3-bis(4-pyridyl)propane (bpp) and 2,5-thiophenedicarboxylic acid (tdc) by slow evaporation at room temperature. The X-ray crystal structures of all three CPs were determined, revealing that they are all comprised of 1D infinite cationic [Ag(L)] chains interspersed with discrete deprotonated tdc2− counterions. These CPs exhibit good photocatalytic performances for the degradation of methylene blue and rhodamine B, giving up to 97% degradation under UV irradiation within 120 min. A possible photocatalytic mechanism is proposed, based on the results of active species capture experiments.


Datum: 01.05.2019


Mixed thioalkyl-azoimine (SNN′)/α-diimine–ruthenium complexes: synthesis, characterization, DFT calculations, crystal structure and application as pre-catalysts for hydrogenation of acetophenone

Abstract

Eight ruthenium complexes having thioalkyl-azoimine (SNN) ligands of two general types have been synthesized: (a) [Ru(L)(bipy)Cl](PF6) where {bipy = bipyridine, L = (2-SR)C6H4N=NC(COCH3)=NC6H4X, R = Ph (X = H, L1, 1; X = CH3, L2, 2; X = F, L3, 3); R = Me, (X = H, L4, 4)} and (b) [Ru(L1)(N–N)Cl](PF6) {N–N = 4,4-dimethyl-2,2′-bipyridine (dmbipy) (5), (1,10-phenanthroline) phen (6), 3,4,7,8-tetramethyl-1,10-phenanthroline (tetrmphen) (7), 5-5-chloro-1,10-phenanthroline (Clphen) (8). The crystal structures for 1 and 6 as well as for L2 are reported; the crystal structures of 1 and 6 show that L1 is bound to the ruthenium center as κ3[S,N,N′]. The complexes have been characterized by IR, UV/Vis and NMR spectroscopy as well as electrochemical (CV) techniques. The effect of groups X, the substituent R and N–N bidentate ligands on the electronic properties of the resulting mononuclear ruthenium complexes was investigated. The catalytic activity of these complexes was tested in the liquid-phase hydrogenation of acetophenone.


Datum: 01.05.2019


Enamines of 1,3-dimethylbarbiturates and their symmetrical palladium(II) complexes: synthesis, characterization and biological activity

Abstract

Three 1,3-dimethylbarbiturate-enamine derivatives and their symmetrical palladium(II) complexes were prepared and characterized by spectroscopic methods. In addition, the structures of the complexes were determined by single-crystal X-ray diffraction. The X-ray diffraction studies revealed the geometry around the Pd(II) atom in each complex is almost perfectly square-planar. Also, the ligands and their palladium(II) complexes were tested for antifungal and antibacterial activity against various clinical and food-borne microorganisms, revealing promising biological activities.


Datum: 01.05.2019


Synthesis, X-ray crystal structure, DFT calculations, spectroscopic characterization and redox behaviour of a rhodium(III) complex of an anthracene–pyridylhydrazone ligand

Abstract

A pyridylhydrazone incorporating an anthracene moiety, designated as HLAnc, has been synthesized in order to examine its coordination behaviour towards rhodium(III). The complex [RhLAnc(PPh3)2Cl2], incorporating a four-membered metallacycle, has been isolated and authenticated by a single-crystal X-ray diffraction study. The complex shows interesting redox and optoelectronic properties, and to better understand these, theoretical investigations have been performed using density functional theory (DFT) and time-dependent DFT. The visible excitation for the complex arises from primarily mixed singlet-manifold 1ILCT and 1LLCT transitions.


Datum: 01.05.2019


 


Category: Current Chemistry Research

Last update: 28.03.2018.






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