Transition Metal Coordination Complexes Research Articles

New compounds constructed from bi-antimony capped Keggin polyoxoanions and different coordination fragments

Two new compounds [Cu(enMe)2][Cu(enMe)2(H2O)][SiMoV6MoVI6Sb2O40] (1) and [Ni(en)2]2[SiMoV6MoVI6Sb2O40] (2) (enMe=1,2-diaminopropane, en=1,2-ethylenediamine) have been hydrothermally synthesized and characterized by IR, UV–Vis spectroscopy, X-ray photoelectron spectroscopy (XPS), powder XRD analyses, elemental analyses and single crystal X-ray diffraction. The two compounds represent the first examples of hybrids based on bi-antimony capped Keggin polyanions {SiMo12Sb2O40} and different transition metal coordination complexes.

Philip John Stephens. 9 October 1940 — 31 July 2012

Philip J. Stephens was a theoretical chemist who brought to fruition two new forms of optical spectroscopy, using circularly polarized light, for the determination of electronic structure and molecular stereochemistry. The first was magnetic circular dichroism (MCD), the wavelength dependence of the differential absorption of left and right circularly polarized light induced by a magnetic field applied parallel to the light beam. Stephens established a methodology for extracting from MCD spectra the angular momentum characteristics of ground and excited electronic states and demonstrated applications to the assignment of the optical spectra of coordination complexes of transition metals and to metalloproteins. In the second half of his career Stephens led the field of vibrational circular dichroism (VCD), the measurement of the natural circular dichroism (CD) arising from the vibrational transitions of chiral molecules. He developed instrumental techniques to measure this weak dichroism over a wide frequency range with high sensitivity. Subsequently he developed a quantum-mechanical method that yielded reliable calculations of VCD spectra by using density functional theory. Thus absolute configurations of all the chiral centres in an organic molecule are readily established. Given the increasing importance of enantiomerically pure chiral drugs, VCD has found widespread application in the pharmaceutical industry. Philip had not only a deep understanding of chemical theory but also a thorough grasp of experiments. His lectures on theoretical topics were models of clarity. He was also an accomplished pianist in demand, when a student at Oxford University, as an accompanist and for chamber concerts.

Three 3D complexes constructed from azelaic aci and rigid bis(imidazole) ligand: Syntheses, structures, thermal and photoluminescent properties

Three new 3D transition metal coordination complexes, namely, [Co(Aze)(L)] ( 1 ), [Cu(Aze)(L)] 2 ( 2 ) and [Cd(Aze)(L)]·3H 2 O ( 3 ) (Aze = azelaic acid, L = 1,4-bis (1-imidazolyl)-benzene) have been synthesized hydrothermally from the self-assembly of the transition metal ions (M 2 + ) with flexible aliphatic dicarboxylate ligand (Aze) and the rigid bis(imidazole) ligand (L). All complexes display three-dimensional (3D) structures. Complex 1 shows a three-fold interpenetrating 4-connected dmp net. Complex 2 shows a noninterpenetrating 4-connected cds net. Complex 3 shows the pcu net built on 6-connected Cd 2 units and particularly there exists weave-like water chains penetrating the channels of the pcu net along b direction. Furthermore, thermogravimetric studies of 1 , 2 and 3 , and photoluminescent property of 3 have also been investigated. Three 3D complexes constructed from azelaic acid and rigid bis(imidazole) ligand are described. Complex 1 displays a 3-fold interpenetrating dmp net. Complex 2 shows a noninterpenetrating cds net. Complex 3 shows the pcu net with weave-like water chains along b direction. The thermogravimetric and photoluminescent properties have also been investigated. ► Three 3D complexes based on azelaic acid and bis(imidazole) ligands are described. ► Complex 1 displays a 3-fold interpenetrating dmp net. ► Complex 2 displays a noninterpenetrating cds net. ► Complex 3 shows a pcu net containing weave-like water chains with photoluminescence.

Syntheses, crystal structures and anticancer activities of three novel transition metal complexes with Schiff base derived from 2-acetylpyridine and l-tryptophan

Abstract Three novel transition metal coordination complexes, Cu(C18H16N3O2)2·2CH3OH (1), Zn(C18H16N3O2)2·2CH3CH2OH (2) and Cd(C18H16N3O2)2·2CH3OH (3) (C18H16N3O2: 2-acetylpyridine-L-tryptophan) have been synthesized and characterized by IR, UV, elemental analysis, 1H NMR and X-ray diffraction single crystal analysis. The three crystals crystallize in the tetragonal crystal system, space group P43212. They are all six-coordinated by two nitrogen atoms from C=N, two nitrogen atoms from pyridine rings and two carboxylic oxygen atoms in different ligands, forming a distorted octahedron geometry. Each ligand serves as a bridging ligand to link metal ions through carboxylic oxygen atoms, leading to a three-dimensional coordination polymer. The anticancer activities of these three complexes on MDA-MB-231 breast cancer cells were also investigated. The results indicate that all of the three complexes can inhibit the cellular proliferation. Furthermore, Cd(C18H16N3O2)2·2CH3OH (3) has the highest anti-proliferative activity among the three complexes. In addition, Cd(C18H16N3O2)2·2CH3OH (3) can inhibit proteasomal chymotrypsin-like activity and also can induce apoptosis on human breast cancer MDA-MB-231 cells.

Syntheses and structural characterizations of three transition metal coordination complexes based on flexible 2,4-dichlorophenoxyacetate (2,4-DCP)

Three transition metal coordination complexes, {[Co(2,4-DCP)2(μ 2-H2O)(H2O)2] · (H2O)2} n (1), [Zn(2,4-DCP)(IN)] n (2), and [Mn2(2,4-DCP)3(DMPY)2(μ 2-H2O)(H2O)] · (2,4-DCP) · 0.2(H2O) (3) (2,4-DCP = 2,4-dichlorophenoxyacetate, IN = isonicotinate, DMPY = 5,5′-dimethyl-2,2′-bipyridine), have been prepared under hydrothermal conditions and characterized by elemental analysis, IR spectroscopy, thermogravimetric analysis, and single-crystal X-ray diffraction. Complex 1 displays a 1-D chain through cobalt and bridging water molecules with Co ··· Co distance of 4.028(2) Å. Complex 2 shows a 2-D (4,4) net, which is extended into a 3-D supramolecular framework by weak hydrogen-bonding interactions. Complex 3 consists of discrete dinuclear cations, 2,4-DCP counter ions and free water molecules, which are assembled into a packing structure through π ··· π stacking of inversion-related DMPY ligands and hydrogen bonds. Magnetic susceptibility measurements show weak antiferromagnetic interactions in 1. The photoluminescence and lifetime of 2 in the solid state have also been studied.

New compounds constructed from polyoxometalates and transition metal coordination complexes with lower positive charge

Five new hybrid compounds constructed from polyoxometalates and transition metal coordination complexes with lower positive charge: [PW11CuO39][Cu(bpy)2]5 (1), [BW12O40][Cu(bpy)2]5 (2) [BW12O40][Cu(Phen)2]3[Cu(Phen)(H2O)]2·2H2O (3), [SiW12O40][Cu(bpy)2]4 (4) and [PW12O40][Cu(bpy)2]4 (5) have been prepared and characterized by IR, UV-Vis, XPS, XRD and single crystal X-ray diffraction analyses. The packing motif of the [Cu(bpy)2]+ copper coordination complexes in compound 1 exhibits square supramolecular channels running along the a axis, which are then filled by the [PW11CuO39]5− ions. Compound 2 is isomorphours with compound 1. Compound 3 contains a novel 2-D supramolecular layer structure constructed from [Cu(Phen)2]+ copper coordination complexes through π⋯π interactions. The packing motif of the [Cu(bpy)2]+ copper coordination complexes in compound 4 exhibits a supramolecular channel which is different from compound 1. Compound 5 is isomorphours with compound 4.

The contrasting chemical reactivity of potent isoelectronic iminopyridine and azopyridine osmium(ii) arene anticancer complexes

A wide variety of steric and electronic features can be incorporated into transition metal coordination complexes, offering the prospect of rationally-designed therapeutic agents with novel mechanisms of action. Here we compare the chemical reactivity and anticancer activity of organometallic OsII complexes [Os(η6-arene)(XY)Z]PF6 where arene = p-cymene or biphenyl, XY = N,N′-chelated phenyliminopyridine or phenylazopyridine derivatives, and Z = Cl or I. The X-ray crystal structure of [Os(η6-p-cym)(Impy-OH)I]PF6·0.5CH2Cl2·H2O (Impy-OH = 4-[(2-pyridinylmethylene)amino]-phenol) is reported. Like the azopyridine complexes we reported recently (Dalton Trans., 2011, 40, 10553–10562), some iminopyridine complexes are also potently active towards cancer cells (nanomolar IC50 values). However we show that, unlike the azopyridine complexes, the iminopyridine complexes can undergo aquation, bind to the nucleobase guanine, and oxidize coenzyme nicotine adenine dinucleotide (NADH). We report the first detection of an Os-hydride adduct in aqueous solution by 1H NMR (−4.2 ppm). Active iminopyridine complexes induced a dramatic increase in the levels of reactive oxygen species (ROS) in A549 lung cancer cells. The anticancer activity may therefore involve interference in the redox signalling pathways in cancer cells by a novel mechanism.

Photophysical properties of MM quadruply bonded complexes (M = Mo, W) supported by carboxylate ligands: charge delocalization and dynamics in S1 and T1 states

Quadruply bonded dinuclear metal complexes of molybdenum and tungsten have the MM configuration σ(2)π(4)δ(2) and a considerable degree of attention has been devoted to studies of the δ → δ(*) transition. For compounds of the type M(2)(O(2)CR)(4), the CO(2) π(*) orbitals introduce a M(2) δ to ligand π(*) transition, a (1)MLCT absorption which may be lower in energy than the δ → δ(*) and is more intense, thus obscuring the observation of the latter. When the R group is a conjugated organic system such as an aryl group, the (1)MLCT shifts to even lower energy and emission is seen from this S(1) state in addition to phosphorescence from the T(1) state which may be either (3)MLCT or (3)MMδδ(*). The latter typically occurs around 1100 nm with a lifetime that ranges from ~1 μs (M = W) to 100 μs (M = Mo). The S(1)(1)MLCT states have lifetimes of ~1-20 ps, allowing for fs and ns studies of the charge distribution/localization with time in both the S(1) and T(1) states, which is quite rare for transition metal coordination complexes. Of particular interest and focus have been complexes of the type trans-M(2)L(2)L'(2) where L and L' are carboxylate or amidinate groups for which only one set of ligands allows for expansive Lπ-M(2)δ-Lπ conjugation and has a low energy (1)MLCT. Compounds of this type have excited states that may be considered as mixed valence (MV) ions [L-M(2)(+)-L(-)] ↔ [L(-)-M(2)(+)-L] where the hole resides on the M(2) unit and the electron is either localized on one ligand, a class I or II MV ion, or is fully delocalized over both ligands, a class III ion in the Robin and Day scheme. Examples of these systems will be described along with the newly prepared complexes trans-M(2)(T(i)PB)(2)(O(2)CC≡C-9-anthracene)(2), M = Mo, W, that have the IR-active reporter groups CO(2) and C≡C.

Syntheses, crystal structures, and properties of four new coordination compounds of transition metals and imidazoledicarboxylic acid derivatives

Four new transition metal coordination complexes, [Cd(H2pimdc)2(H2O)2] · 4H2O (1), [Zn(H2pimdc)2(H2O)2]2 · 7H2O (2), and [M(H2pimdc)2] (M = Cu (3) or Ni (4), H2pimdc− = 2-propyl-4,5-imidazoledicarboxylate), have been prepared by conventional synthesis and characterized by elemental analyses, IR, TG, and single-crystal X-ray diffraction. H2pimdc− is a bidentate chelating ligand in 1 and 2, leading to 3-D supramolecular structures through hydrogen bonds. However, H2pimdc− is a tridentate chelating-bridge ligand in 3 and 4, which exhibit 2-D layer structures. Thermal properties and photoluminescence spectra of 1–4 were measured.

Metal Complexes as DNA Intercalators

DNA has a strong affinity for many heterocyclic aromatic dyes, such as acridine and its derivatives. Lerman in 1961 first proposed intercalation as the source of this affinity, and this mode of DNA binding has since attracted considerable research scrutiny. Organic intercalators can inhibit nucleic acid synthesis in vivo, and they are now common anticancer drugs in clinical therapy. The covalent attachment of organic intercalators to transition metal coordination complexes, yielding metallointercalators, can lead to novel DNA interactions that influence biological activity. Metal complexes with σ-bonded aromatic side arms can act as dual-function complexes: they bind to DNA both by metal coordination and through intercalation of the attached aromatic ligand. These aromatic side arms introduce new modes of DNA binding, involving mutual interactions of functional groups held in close proximity. The biological activity of both cis- and trans-diamine Pt(II) complexes is dramatically enhanced by the addition of σ-bonded intercalators. We have explored a new class of organometallic "piano-stool" Ru(II) and Os(II) arene anticancer complexes of the type [(η(6)-arene)Ru/Os(XY)Cl](+). Here XY is, for example, ethylenediamine (en), and the arene ligand can take many forms, including tetrahydroanthracene, biphenyl, or p-cymene. Arene-nucleobase stacking interactions can have a significant influence on both the kinetics and thermodynamics of DNA binding. In particular, the cytotoxic activity, conformational distortions, recognition by DNA-binding proteins, and repair mechanisms are dependent on the arene. A major difficulty in developing anticancer drugs is cross-resistance, a phenomenon whereby a cell that is resistant to one drug is also resistant to another drug in the same class. These new complexes are non-cross-resistant with cisplatin towards cancer cells: they constitute a new class of anticancer agents, with a mechanism of action that differs from the anticancer drug cisplatin and its analogs. The Ru-arene complexes with dual functions are more potent towards cancer cells than their nonintercalating analogs. In this Account, we focus on recent studies of dual-function organometallic Ru(II)- and Os(II)-arene complexes and the methods used to detect arene-DNA intercalation. We relate these interactions to the mechanism of anticancer activity and to structure-activity relationships. The interactions between these complexes and DNA show close similarities to those of covalent polycyclic aromatic carcinogens, especially to N7-alkylating intercalation compounds. However, Ru-arene complexes exhibit some new features. Classical intercalation and base extrusion next to the metallated base is observed for {(η(6)-biphenyl)Ru(ethylenediamine)}(2+) adducts of a 14-mer duplex, while penetrating arene intercalation occurs for adducts of the nonaromatic bulky intercalator {(η(6)-tetrahydroanthracene)Ru(ethylenediamine)}(2+) with a 6-mer duplex. The introduction of dual-function Ru-arene complexes introduces new mechanisms of antitumor activity, novel mechanisms for attack on DNA, and new concepts for developing structure- activity relationships. We hope this discussion will stimulate thoughtful and focused research on the design of anticancer chemotherapeutic agents using these unique approaches.

Cobalt(III)-oxo cubane clusters as catalysts for oxidation of organic substrates

Transition metal coordination complexes play a vital role as catalysts in the oxidation of organic substrates including renewable chemicals in an economically viable and environmentally friendly way. Here we highlight the preparation, characterization and application of oxo-cubane complexes of cobalt(III) as oxidation catalysts using air and water as oxidants. Cobalt(III)-oxo complexes of the type Co4O4(O2CR)4L4 have been prepared by a general method and these have been characterized by analytical, spectroscopic, electrochemical and crystallographic methods. These soluble complexes have shown promising utility as catalysts in the aerobic oxidation of side chains of alkylaromatic hydrocarbon compounds. Oxidation of neat ethylbenzene has shown very high conversion and selectivity for acetophenone formation. On the other hand, oxidation of p-xylene has been found to yield both p-toluic acid and terephthalic acid. It is also possible to oxidize p-xylene in an aqueous medium under moderate applied O2 pressure. Selective epoxidation of α-pinene with air as the oxidant also takes place with the cobalt(III)-based homogeneous catalysts. Preparation of cobalt(III)-oxo complexes of the type Co4O4(O2CR)4L4 and their characterization by analytical, spectroscopic, electrochemical and crystallographic methods are described. Catalytic applications of the oxo-cubane complexes are also highlighted. These soluble complexes have shown promising utility as catalysts in the aerobic oxidation of side chains of alkylaromatic hydrocarbon compounds such as ethylbenzene and p-xylene. Selective epoxidation of α-pinene with air as the oxidant also takes place with the cobalt(III)-based homogeneous catalysts.

Study of the Conformationally Flexible, Wide Bite-Angle Diphosphine 4,6-Bis(3-diisopropylphosphinophenyl)dibenzofuran in Rhodium(I) and Palladium(II) Coordination Complexes

The diphosphine 4,6-bis(3-diisopropylphosphinophenyl)dibenzofuran (abbreviated as (iPr)DPDBFphos) was prepared and studied for its potential as a trans-chelating ligand in transition-metal coordination complexes. In the rhodium norbornadiene complex [((iPr)DPDBFphos)Rh(NBD)]BF(4), which has been characterized with multinuclear NMR spectroscopy, X-ray crystallography, and electrochemical studies, the ligand binds in cis fashion. In the bis(acetonitrile) complexes of rhodium and palladium [((iPr)DPDBFphos)M(CH(3)CN)(2)](BF(4))(n) (M = Rh, Pd; n = 1, 2), the ligand adopts a trans coordination geometry. Density functional theory (DFT, M06-L) calculations predict that the trans conformer is energetically more favorable than the cis by 3.5 kcal/mol. Cyclic voltammograms of the bis(acetonitrile) Pd(II) and Rh(I) complexes contain reversible and quasi-reversible reduction events, respectively, which are preliminarily assigned as metal-based redox reactions.

Two new hybrid compounds assembled from Keggin-type polyoxometalates and transition metal coordination complexes

Two new hybrid compounds based on Keggin-type polyoxometalates: {[PMo 12O 40][Ni( Phen) 2(H 2O)] 2}·K·2OH − ( 1) and [Cd 2( Phen) 4Cl 2][HPW 12O 40]·H 2O ( 2) ( Phen=1,10-phenanthroline), have been prepared and characterized by IR, UV–vis, XPS, XRD and single crystal X-ray diffraction analyses. Compound 1 exhibits a 1-D chain structure constructed from Pseudo-Keggin polyoxometalate bi-supported transition metal coordination complexes linked by K + ions. Compound 2 contains Pseudo-Keggin polyoxoanions [HPW 12O 40] 2− and novel metal–chloride–ligand coordination complexes [Cd 2( Phen) 4Cl 2] 2+.

A series of dn transition metal coordination complexes: Structures and comparative study of surface electron behaviors (n = 9, 8, 7, 6, 5)

Ten transition metal coordination complexes [Cu2(phen)(p-tpha)(μ-O)]n1, [Cu(m-tpha)(imH)2]n2, [Ni(5-Haipa)2(H2O)2]n3, [Ni(phen)2(H2O)2]·btc·[Ni(H2O)6]0.5·9H2O 4, [Co(2,5-pdc)(H2O)2]n·nH2O 5, [Co2(2,5-pdc)2(H2O)6]n·2nH2O 6, [Fe(2,5-Hpdc)2(H2O)2]·H2O 7, [Co(C6H4NO2)3]·H2O 8, [Fe2(μ2-btec)(μ2-H2btec)(bipy)2(H2O)2]n9, [Mn(phen)(2,5-pdc)(H2O)2]·H2O 10 (H4btec=1,2,4,5-benzenetetracarboxylic acid, phen=1,10-phenanthroline, 2,5-H2pdc=2,5-pyridine-dicarboxylic acid, p-tpha=p-phthalic acid, m-tpha=m-phthalic acid, bipy=2,2′-bipyridine, 5-H2aipa=5-aminoisophthalic acid, imH=imidazole, H3btc=1,3,5-benzenetricarboxylic acid) were synthesized through hydrothermal method. They were characterized by UV–Vis absorption spectra, single-crystal X-ray diffraction and surface photovoltage spectra (SPS). Structural analysis indicated that the complexes 1, 2, 3, 5, 6 and 9 were linked into infinite structures bridged by organic acid ligands. The other four complexes were molecular complexes and further connected to 2D or 3D structures by the hydrogen bonds. The SPS of complexes 1–10 indicate that there are positive response bands in the range of 300–800nm showing different levels of photo-electric conversion properties. The intensity, position, shape and the number of the response bands in SPS are obviously different since the structure, species, valence, dn electrons configuration and coordinated environment of the center metals are different. There are good relationships between SPS and UV–Vis spectra.

A new compound based on Preyssler-type P5W30 anion modified by CoII and flexible bis(benzimidazole) ligand

Abstract A new Preyssler-type polyoxometalates-based inorganic–organic hybrid compound [Co(Hbbbm)2(H2O)2(H2P5W30O110)]2·9H2bbbm·20H2O ( 1 ) [bbbm = 1,1′-(1,4-butanediyl)bis-1 H-benzimidazole] has been synthesized under hydrothermal conditions and characterized by IR, TG and XRD. Single crystal X-ray diffraction analysis reveals that compound 1 is composed of two Preyssler-type [H2P5W30O110]13− anions (P5W30), two [Co(Hbbbm)2(H2O)2]4+ cations, nine discrete protonated [H2bbbm]2+ molecules and twenty crystallization water molecules. Two P5W30 anions are covalently bridged by two [Co(Hbbbm)2(H2O)2]4+ cationic fragments to form a P5W30-based dimer. The dimers are ultimately extended to a three dimensional (3D) network by π∙∙∙π stacking and hydrogen-bonding interactions. Compound 1 represents the first bisupporting Preyssler-type structure modified by transition metal coordination complex (TMC). Additionally, the electrochemical behavior and electrocatalysis of compound 1 have been investigated.

Interfacial organic layers: Tailored surface chemistry for nucleation and growth

The interfaces between inorganic and organic materials are important to a wide variety of technologies. A significant challenge concerns the formation of these interfaces when the inorganic layer must be grown on a pre-existing organic layer. In this review the authors focus on fundamental aspects of inorganic-organic interface formation using transition metal coordination complexes and atomic layer deposition. First, the authors discuss aspects of the synthesis and characterization of ultrathin interfacial organic layers, formed mostly on SiO2 and possessing a variety of functional groups, including layers with a branched microstructure. The authors go on to discuss the reactions of transition metal coordination complexes with these layers. A number of factors control the uptake of the transition metal complex and the composition of the adsorbed species that are formed. These include the identity, density, and dimensionality or spatial distribution of the functional groups. At room temperature, adsorption on layers that lack functional groups results in the penetration of the organic layer by the transition metal complex and the reaction with residual OH at the organic/SiO2 interface. Adsorption on layers with a mostly two-dimensional arrangement of reactive functional groups results in the formation of molecular “bipods,” where the surface bound functional groups react with the complex via two ligand exchange reactions. In contrast, for layers that possess a high density of functional groups arranged three dimensionally, the transition metal complex can be virtually stripped of its ligands. Atomic layer deposition on interfacial organic layers also depends strongly on the density and accessibility of reactive functional groups. On surfaces that possess a high density of functional groups, deployed two dimensionally, growth via atomic layer deposition is initially weakly attenuated, mostly uniform and smooth, and eventually evolves to growth characteristic of unmodified SiO2. Growth on layers that lack sufficient densities of functional groups is initially strongly attenuated, in contrast, and the resulting films are rough, severely islanded and three dimensional. As a consequence, there is a correlation between the strength of the initial attenuation in the rate of growth and the thin film morphology. Correlations between the initial uptake of the transition metal complex by the organic layer and the initial rate of thin film growth are less direct, however, as the composition and structure of the chemisorbed species must also be considered.

A novel polyoxometalate tri-supported mixed-valent transition metal coordination complex

A new compound [Mo 8 V 7 O 42 ][Cu(2,2′-bpy) 2 ] 2 [Cu(2,2′-bpy)]·2H 3 O ( 1 ) has been synthesized under hydrothermal conditions and characterized by IR, UV–vis spectrum, elemental analysis, XRD, ESR, XPS, X-ray diffraction analysis and magnetic property study. Single-crystal X-ray structure analysis indicates that the compound 1 is a novel Keggin polyoxoanion tri-supported mixed-valent transition metal coordination complex. The first Keggin polyoxometalate supported mixed-valent transition metal coordination complex has been hydrothermally synthesized and characterized by IR, XPS, XRD, ESR, UV–vis, elemental analysis, single-crystal X-ray diffraction analysis and magnetic property study.

A copper–cyclen coordination complex associated with a polyoxometalate anion: Synthesis, crystal structure and electrochemistry of [Cu(cyclen)(MeCN)][W6O19

Abstract The reaction between Cu(NO 3 ) 2 ·3H 2 O and a tetra-aza macrocycle, more specifically, cyclen in 1:1 MeCN–MeOH solvent mixture forms a Cu 2+ –cyclen coordination complex in situ , that has been reacted with an isopolyanion [W 6 O 19 ] 2− in a slow diffusion technique, resulting in the isolation of an ion-pair solid [Cu(cyclen)(MeCN)][W 6 O 19 ] ( 1 ). Single crystal structural investigation on 1 shows a square pyramidal geometry around the metal centre (copper ion) with an axially bound MeCN solvent molecule. The title compound 1 is the first crystallographically characterized ion-pair compound, in which a transition metal coordination complex of a tetra-aza-crown ether (cyclen) has been associated with a polyoxometalate cluster anion. This communication deals with synthesis, spectroscopic, structural and electrochemical analyses of compound 1 .

Hydrogen bonding effects on topological structures of two supramolecular transition metal coordination complexes based on organosulphonate ligands

Abstract The syntheses, X-ray crystal structures and topological analyses of two supramolecular coordination complexes, [Co(H2O)4(ps)2] 1 and [Cu(H2O)2(ps)2] 2 (ps− = pyridine-3-sulfonic anion), are reported. Although the basic coordination environments and patterns around the metal centers of 1 and 2 are similar, the overall topologies of the two complexes are very different due to the formation of distinct hydrogen bonding interactions resulting from organosulphonate ligands.

0D and 1D dimensional structures based on the combination of polyoxometalates, transition metal coordination complexes and organic amines

Five novel heteropolyanions have been synthesized and characterized by IR, UV-vis, XPS spectroscopy, XRD, and elemental analyses. Single-crystal X-ray diffraction analyses reveal that these five compounds represent novel examples of compounds based on the combination of polyoxometalates, transition metal coordination complexes and organic amines. Of which 1, 2 and 3 exhibit 0D structures of polyoxometalate supported transition metal coordination complexes, while 4 and 5 exhibit novel 1D structures constructed from polyoxometalates and transition metal coordination complexes.