Di‐μ‐chlorido‐bis({2‐[1‐(2‐pyridylethylimino)ethyl]pyrrolato‐κ3N,N′,N′′}copper(II))

The title compound, [Cu₂(C₁₃H₁₄N₃)₂Cl₂], is a neutral dimeric copper(II) complex. The two Cu^II atoms are asymmetrically bridged by two chloride ions. Each Cu^II atom is also bound to the three N atoms of a deprotonated tridentate Schiff base ligand, giving a distorted square‐pyramidal N₃Cl₂ coordination environment overall. The dinuclear complex lies across an inversion centre in the space group P. This work demonstrates the effect of ligand flexibility and steric constraints on the structures of copper(II) complexes.     

A New Sulfur‐containing Schiff‐Base Ligand and Binding to Copper(II) and Cobalt(II)

A new Schiff‐base ligand having a potentially coordinating thioether group (2‐quinoline‐N‐(2′‐methylthiophenyl)methyleneimine, qmtpm ) has been prepared. The synthesis, structure, UV‐Vis and EPR studies of one copper(II) and two cobalt(II) complexes from this ligand is reported. The X‐ray structures of the Cu^II and Co^II chlorido complexes 1 and 2 reveal the metal atoms in highly distorted square‐pyramidal environments constituted of one tridentate ligand and two anions. On the other hand, the thiocyanato Co^II compound 3 exhibits a distorted trigonal‐bipyramidal structure. These structural variations are apparently due to the different counter‐ions which leads to distinct lattice interactions. The spectroscopic data obtained by EPR and UV‐Vis investigations are in agreement with the solid‐state structures of the coordination compounds.     

Synthesis,Crystal Structure,Thermal, Spectroscopic and Magnetic Properties of a 2D Grid‐like Copper(II) μ‐1,1 Isocyanato Coordination Polymer with Pyrazine Bridges

Reaction of copper(II) cyanate with pyrazine leads to the formation of [Cu(NCO)₂(pyrazine)]_n ( 1 ), in which the Cu²⁺ cations are coordinated by two nitrogen atoms of the pyrazine ligands, as well as by four nitrogen atoms of the cyanate anions within a slightly distorted octahedral coordination. In the crystal structure the Cu²⁺ cations are connected by the pyrazine ligands into chains which are further linked by the cyanate anions through asymmetric μ‐1,1‐NCO coordination into layers. On heating compound 1 transforms quantitatively to copper(II) cyanate which decompose to elemental copper on further heating. No ligand deficent intermediates are observed. Magnetic measurements reval an antiferromagnetic ordering at lower temperatures mediated by the π‐system of the aromatic pyrazine ligand as well as net ferromagnetic interactions mediated by the μ‐1,1‐NCO bridging cyanato anions. A search in the Cambridge Crystal Structure Database shows that the terminal coordination mode in cyanato complexes as well as their azido and thiocyanato analogs is obviously energetically favored. In addition, a comparison of their symmetric and asymmetric end‐on (μ‐1,1) as well as end‐to‐end (μ‐1,3) bridging modes reveal interesting correlations.     

Synthesis,Spectral, Thermal Studies of Co(II), Ni(II), Cu(II) and Zn(II)‐arginato Complexes. Crystal Structure of Monoaquabis(arginato‐κO,κN)copper(II). [Cu(arg)2(H2O)].NaNO3

Transition metal complexes of arginine (using Co(II), Ni(II), Cu(II) and Zn(II) cations separately) were synthesized and characterized by FTIR, TG/DTA‐DrTG, UV‐Vis spectroscopy and elemental analysis methods. Cu(II)‐Arg complex crystals was found suitable for x‐ray diffraction studies. It was contained, one mole Cu^II and Na⁺ ions, two arginate ligands, one coordinated aqua ligand and one solvent NO₃^? group in the asymmetric unit. The principle coordination sites of metal atom have been occupied by two N atoms of arginate ligands, two carboxylate O atoms, while the apical site was occupied by one O atom for Cu^II cation and two O atoms for Co^II, Ni^II, Zn^II atoms of aqua ligands. Although Cu^II ion adopts a square pyramidal geometry of the structure. Co^II, Ni^II, Zn^II cations have octahedral due to coordination number of these metals. Neighbouring chains were linked together to form a three‐dimensional network via hydrogen‐bonding between coordinated water molecule, amino atoms and O atoms of the bridging carboxylate groups. Cu^II complex was crystallized in the monoclinic space group P2₁, a = 8.4407(5) Å, b = 12.0976(5) Å, c = 10.2448(6) Å, V = 1041.03(10) ų, Z = 2. Structures of the other metal complexes were similar to CuII complex, because of their spectroscopic studies have in agreement with each other. Copper complex has shown DNA like helix chain structure. Lastly, anti‐bacterial, anti‐microbial and anti‐fungal biological activities of complexes were investigated.     

Template-directed synthesis of macrocyclic copper(II) complexes of diazacyclam, 1,3,6,10,12,15-hexaazatricyclo[13.3.1.16,10]eicosane

Template reaction of copper(II) nitrate with N-(2-aminoethyl)-1,3-diaminopropane and formaldehyde yields a macrocyclic copper(II) complex of 1,3,6,10,12,15-hexaazatricyclo[13.3.1.1^6,10]eicosane (L), [CuL(NO₃)₂] (1). Replacement of nitrate with perchlorate gives [CuL(ClO₄)₂] (2). These complexes have been characterized by FT-IR and Raman spectroscopies, electronic absorption, cyclic voltammetry, and X-ray crystallography. The crystal structure of 1 shows that copper has distorted octahedral geometry with two secondary and two tertiary amines of the macrocycle and two oxygen atoms from nitrate coordinating the axial positions. The copper in 2 has the same geometry with axial positions occupied by one oxygen atom of perchlorate. Copper lies on the plane of four coordinated nitrogen atoms and there is no rms deviation from this plane. Cyclic voltammetry of 1 and 2 gives two one-electron waves corresponding to Cu^II/Cu^III (?0.75,??0.72) and Cu^II/Cu^I (0.48, 0.24) processes. For understanding of geometry parameters in diazacyclam-based copper(II) complexes, a survey on complexes from CSD structures is presented. In this study the macrocycle hole size was estimated by ionic radii of metal ions located inside of it.     

Cu3(CN)4(NH3)2Hg(CN)2: a novel inter­penetrating framework formed from CuI,CuII, HgII and cyanide bridges

The title compound, poly[diammine­hexa‐μ‐cyano‐di­copper(I)­copper(II)­mercury(II)], [Cu₃Hg(CN)₆(NH₃)₂]_n, has a novel threefold‐inter­penetrating structure of three‐dimensional frameworks. This three‐dimensional framework consists of two‐dimensional network Cu₃(CN)₄(NH₃)₂ complexes and rod‐like Hg(CN)₂ complexes. The two‐dimensional network complex contains trigonal–planar Cu^I (site symmetry m) and octa­hedral Cu^II (site symmetry 2/m) in a 2:1 ratio. Two types of cyanide group form bridges between three coordination sites of Cu^I and two equatorial sites of Cu^II to form a two‐dimensional structure with large hexa­gonal windows. One type of CN⁻ group is disordered across a center of inversion, while the other resides on the mirror plane. Two NH₃ mol­ecules (site symmetry 2) are located in the hexa­gonal windows and coordinate to the remaining equatorial sites of Cu^II. Both N atoms of the rod‐like Hg(CN)₂ group (Hg site symmetry 2/m and CN⁻ site symmetry m) coordinate to the axial sites of Cu^II. This linkage completes the three‐dimensional framework and penetrates two hexa­gonal windows of two two‐dimensional network complexes to form the threefold‐inter­penetrating structure.     

A new stepped tetranuclear copper(II) complex: synthesis,crystal structure and photoluminescence properties

Binuclear and tetranuclear copper(II) complexes are of interest because of their structural, magnetic and photoluminescence properties. Of the several important configurations of tetranuclear copper(II) complexes, there are limited reports on the crystal structures and solid‐state photoluminescence properties of `stepped' tetranuclear copper(II) complexes. A new Cu^II complex, namely bis{μ₃‐3‐[(4‐methoxy‐2‐oxidobenzylidene)amino]propanolato}bis{μ₂‐3‐[(4‐methoxy‐2‐oxidobenzylidene)amino]propanolato}tetracopper(II), [Cu₄(C₁₁H₁₃NO₃)₄], has been synthesized and characterized using elemental analysis, FT–IR, solid‐state UV–Vis spectroscopy and single‐crystal X‐ray diffraction. The crystal structure determination shows that the complex is a stepped tetranuclear structure consisting of two dinuclear [Cu₂(L )₂] units {L is 3‐[(4‐methoxy‐2‐oxidobenzylidene)amino]propanolate}. The two terminal Cu^II atoms are four‐coordinated in square‐planar environments, while the two central Cu^II atoms are five‐coordinated in square‐pyramidal environments. The solid‐state photoluminescence properties of both the complex and 3‐[(2‐hydroxy‐4‐methoxybenzylidene)amino]propanol (H₂L ) have been investigated at room temperature in the visible region. When the complex and H₂L are excited under UV light at 349 nm, the complex displays a strong blue emission at 469 nm and H₂L displays a green emission at 515 nm.     

Poly[(μ‐pentafluorobenzoato‐κ2O:O′)(pentafluorobenzoato‐κO)(μ‐pyrazine‐κ2N:N′)copper(II)]: a coordination polymer linked into a three‐dimensional network by intermolecular C—H...F—C interactions

In the title compound, [Cu(C₆F₅COO)₂(C₄H₄N₂)]_n, (I), the asymmetric unit contains one Cu^II cation, two anionic pentafluorobenzoate ligands and one pyrazine ligand. Each Cu^II centre is five‐coordinated by three O atoms from three independent pentafluorobenzoate anions, as well as by two N atoms from two pyrazine ligands, giving rise to an approximately square‐pyramidal coordination geometry. Adjacent Cu^II cations are bridged by a pyrazine ligand and two pentafluorobenzoate anions to give a two‐dimensional layer. The layers are stacked to generate a three‐dimensional supramolecular architecture via strong intermolecular C—H...F—C interactions, as indicated by the F...H distance of 2.38 Å.     

Synthesis and structural studies of (2 E ,3 E ,6 R ,9 E ,11 E )-6-isopropenyl-3,6,10-trimethyl-5,8-dioxa-4,9-diazadodeca-3,9-diene-2,11-dione dioxime, ligand and its Mono-, homo, and heterodinuclear copper(II)/nickel(II) complexes

This article describes the synthesis of a new (2E,3E,6R,9E,11E)-6-isopropenyl-3,6,10-trimethyl-5,8-dioxa-4,9-diazadodeca-3,9-diene-2,11-dione dioxime (H₂hmdm), and its mono-, homo, and heterodinuclear copper(II)/nickel(II) complexes. Elemental analyses, stoichiometric and spectroscopic data of the metal complexes indicated that the metal ions are coordinated to the oxime and imine nitrogen atoms (C=N). The Cu(H₂hmdm), molecule coordinates to the second copper(II) ion through the oximate oxygens to afford a binuclear structure doubly bridged by the oximate groups in the cis arrangement. In the dinuclear complexes, in which the first Cu^II ion was complexed with nitrogen atoms of the oxime and imine groups, the second Cu^II ion is ligated with the 1,10-phenanthroline nitrogen atoms. Ligand and its mononuclear copper(II), homo and heterodinuclear copper(II)–nickel(II) complexes of (H₂hmdm) were characterized by elemental analyses, magnetic moments, ¹H-n.m.r. and ¹³C-n.m.r., i.r., and mass spectral studies. The data support the proposed structure of H₂hmdm and its complexes.     

Copper(II) Complexes with N‐(9‐anthracenyl)‐N′‐(3‐pyridyl)urea (L) and a Derivative of L: Synthesis,Structure, and Fluorescent Properties

Three copper(II) complexes, [Cu₂(OAc)₄L₂] · 2CH₃OH ( 1 ), [CuBr₂L′₂(CH₃OH)] · CH₃OH ( 2a ), and [CuBr₂L′₂(DMSO)] · 0.5CH₃OH ( 2b ) {L = N‐(9‐anthracenyl)‐N′‐(3‐pyridyl)urea and L′ = N‐[10‐(10‐methoxy‐anthronyl)]‐N′‐(3‐pyridyl)urea} have been synthesized by the reaction of L with the corresponding copper(II) salts. Complex 1 shows a dinuclear structure with a conventional “paddlewheel” motif, in which four acetate units bridge the two Cu^II ions. In complexes 2a and 2b , the anthracenyl ligand L has been converted to an anthronyl derivative L′, and the central metal ion exhibits a distorted square pyramidal arrangement, with two pyridyl nitrogen atoms and two bromide ions defining the basal plane and the apical position is occupied by a solvent molecule (CH₃OH in 2a and DMSO in 2b ).     

(2,2′‐Biquinoline‐κ2N,N′)dichloropalladium(II), ‐copper(II) and ‐zinc(II)

In the three title complexes, namely (2,2′‐biquinoline‐κ²N,N′)dichloro­palladium(II), [PdCl₂(C₁₈H₁₂N₂)], (I), and the corresponding copper(II), [CuCl₂(C₁₈H₁₂N₂)], (II), and zinc(II) complexes, [ZnCl₂(C₁₈H₁₂N₂)], (III), each metal atom is four‐coordinate and bonded by two N atoms of a 2,2′‐biquinoline molecule and two Cl atoms. The Pd^II atom has a distorted cis‐square‐planar coordination geometry, whereas the Cu^II and Zn^II atoms both have a distorted tetra­hedral geometry. The dihedral angles between the N—M—N and Cl—M—Cl planes are 14.53 (13), 65.42 (15) and 85.19 (9)° for (I), (II) and (III), respectively. The structure of (II) has twofold imposed symmetry.     

Key Intermediate Species Reveal the Copper(II)‐Exchange Pathway in Biorelevant ATCUN/NTS Complexes

The amino‐terminal copper and nickel/N‐terminal site (ATCUN/NTS) present in proteins and bioactive peptides exhibits high affinity towards Cu^II ions and have been implicated in human copper physiology. Little is known, however, about the rate and exact mechanism of formation of such complexes. We used the stopped‐flow and microsecond freeze‐hyperquenching (MHQ) techniques supported by steady‐state spectroscopic and electrochemical data to demonstrate the formation of partially coordinated intermediate Cu^II complexes formed by glycyl–glycyl–histidine (GGH) peptide, the simplest ATCUN/NTS model. One of these novel intermediates, characterized by two‐nitrogen coordination, t_1/2≈100 ms at pH 6.0 and the ability to maintain the Cu^II/Cu^I redox pair is the best candidate for the long‐sought reactive species in extracellular copper transport.     

Metallkomplexe naphthyl‐substituierter Thioharnstoffderivate

Metal Complexes of Naphthyl‐substituted Thiourea Derivatives The thiourea derivative N, N‐diethyl‐N′‐2‐naphthoylthiourea ( 1 ) and three N‐(dialkylaminothiocarbonyl)‐N′‐(1‐naphthyl)‐arylamidines ( 2 ‐ 4 ) have been synthesized and Cu^II‐, Ni^II‐ and Pd^II‐complexes of them have been prepared. According to the X‐ray structure analyses 1 with Cu^II and Ni^II under deprotonation forms neutral bis‐chelates of nearly square‐planar coordination with a cis arrangement of the O and S ligator atoms. Using their N and S atoms in 1, 3 position as ligators, 2 ‐ 4 in deprotonated form coordinate to Cu^II and Pd^II as neutral bis‐chelates, in the case of Cu^II with a distorted tetrahedral coordination. Pd^II is coordinated square planar and has, probably due to the spatial influence of the 1‐naphthyl groups, a trans arrangement of the N and S ligator atoms.     

Oligo-m-phenyleneoxalamide copper(II) mesocates as electro-switchable ferromagnetic metal-organic wires

Double‐stranded copper(II) string complexes of varying nuclearity, from di‐ to tetranuclear species, have been prepared by the Cu^II‐mediated self‐assembly of a novel family of linear homo‐ and heteropolytopic ligands that contain two outer oxamato and either zero ( 1 b ), one ( 2 b ), or two ( 3 b ) inner oxamidato donor groups separated by rigid 2‐methyl‐1,3‐phenylene spacers. The X‐ray crystal structures of these Cu^II_n complexes (n=2 ( 1 d ), 3 ( 2 d ), and 4 ( 3 d )) show a linear array of metal atoms with an overall twisted coordination geometry for both the outer CuN₂O₂ and inner CuN₄ chromophores. Two such nonplanar all‐syn bridging ligands 1 b – 3 b in an anti arrangement clamp around the metal centers with alternating M and P helical chiralities to afford an overall double meso‐helicate‐type architecture for 1 d – 3 d . Variable‐temperature (2.0–300 K) magnetic susceptibility and variable‐field (0–5.0 T) magnetization measurements for 1 d – 3 d show the occurrence of S=nS_Cu (n=2–4) high‐spin ground states that arise from the moderate ferromagnetic coupling between the unpaired electrons of the linearly disposed Cu^II ions (S_Cu=1/2) through the two anti m‐phenylenediamidate‐type bridges (J values in the range of +15.0 to 16.8 cm^?1). Density functional theory (DFT) calculations for 1 d – 3 d evidence a sign alternation of the spin density in the meta‐substituted phenylene spacers in agreement with a spin polarization exchange mechanism along the linear metal array with overall intermetallic distances between terminal metal centers in the range of 0.7–2.2 nm. Cyclic voltammetry (CV) and rotating‐disk electrode (RDE) electrochemical measurements for 1 d – 3 d show several reversible or quasireversible one‐ or two‐electron steps that involve the consecutive metal‐centered oxidation of the inner and outer Cu^II ions (S_Cu=1/2) to diamagnetic Cu^III ones (S_Cu=0) at relatively low formal potentials (E values in the range of +0.14 to 0.25 V and of +0.43 to 0.67 V vs. SCE, respectively). Further developments may be envisaged for this family of oligo‐m‐phenyleneoxalamide copper(II) double mesocates as electroswitchable ferromagnetic ‘metal–organic wires’ (MOWs) on the basis of their unique ferromagnetic and multicenter redox behaviors.     

Metal(II) Ion Complexes with 5‐(Pyrazin‐2‐yl)‐2,4‐dihydro‐3H‐1,2,4‐triazole‐3‐thione; Synthesis,Structural Characterization,Acid‐base,and Complexing Properties in Solution

The study reports the synthesis of complexes Co(HL)Cl₂ ( 1 ), Ni(HL)Cl₂ ( 2 ), Cu(HL)Cl₂ ( 3 ), and Zn(HL)₃Cl₂ ( 4 ) with the title ligand, 5‐(pyrazin‐2‐yl)‐1,2,4‐triazole‐5‐thione (HL), and their characterization by elemental analyses, ESI‐MS (m/z), FT‐IR and UV/Vis spectroscopy, as well as EPR in the case of the Cu^II complex. The comparative analysis of IR spectra of the metal ion complexes with HL and HL alone indicated that the metal ions in 1 , 2 , and 3 are chelated by two nitrogen atoms, N(4) of pyrazine and N(5) of triazole in the thiol tautomeric form, whereas the Zn^II ion in 4 is coordinated by the non‐protonated N(2) nitrogen atom of triazole in the thione form. pH potentiometry and UV/Vis spectroscopy were used to examine Co^II, Ni^II, and Zn^II complexes in 10/90 (v/v) DMSO/water solution, whereas the Cu^II complex was examined in 40/60 (v/v) DMSO/water solution. Monodeprotonation of the thione triazole in solution enables the formation of the L:M = 1:1 species with Co^II, Ni^II and Zn^II, the 2:1 species with Co^II and Zn^II, and the 3:1 species with Zn^II. A distorted tetrahedral arrangement of the Cu^II complex was suggested on the basis of EPR and Vis/NIR spectra.     

Poly[[aqua‐μ3‐2,2‐dimethylmalonato‐copper(II)] monohydrate] and poly[aqua‐μ3‐2,2‐dimethylmalonato‐copper(II)]

The coordination mode of the dimethylmalonate ligand in the two title Cu^II complexes, {[Cu(C₅H₃O₄)(H₂O)]·H₂O}_n, (I), and [Cu(C₅H₃O₄)(H₂O)]_n, (II), is the same, with chelated six‐membered, bis‐monodentate and bridging bonding modes. However, the coordination environment of the Cu^II atoms, the connectivity of their metal–organic frameworks and their hydrogen‐bonding interactions are different. Complex (I) has a perfect square‐pyramidal Cu^II environment with the aqua ligand in the apical position, and only one type of square grid consisting of Cu^II atoms linked via carboxylate bridges to three dimethylmalonate ligands, with weak hydrogen‐bond interactions within and between its two‐dimensional layers. Complex (II) has a coordination geometry that is closer to square pyramidal than trigonal bipyramidal for its Cu^II atoms with the aqua ligand now in the basal plane. Its two‐dimensional layer structure comprises two alternating grids, which involve two and four different dimethylmalonate anions, respectively. There are strong hydrogen bonds only within its layers.     

Poly[μ2‐chloro‐μ2‐1,4‐oxathiane‐κ2S:S‐copper(I)]

The title complex, [CuCl(C₄H₈OS)]_n, contains infinite spiral (CuS)_n chains linked by bridging Cl atoms into layers. The Cl atoms do not form polymeric fragments with Cu^I, but combine into isolated centrosymmetric Cu₂Cl₂ units. The compound is non‐isomorphous with the Br‐containing analogue, which contains Cu₈S₈ rings linked by Br atoms into chains. The O atom of the 1,4‐oxathiane mol­ecule does not realize its coordination abilities in the known copper(I)–halide complexes, while in copper(II)–halide complexes, oxathiane is coordinated via the S and O atoms. This falls into a pattern of the preferred inter­actions, viz. weak acid (Cu^I atom) with weak base (S atom) and harder acid (Cu^II atom) with harder base (O atom).     

A novel binuclear copper complex incorporating a nalidixic acid derivative displaying a one‐dimensional coordination polymeric structure

The identification of the antibacterial action of nalidixic acid (nx) was central to the development of the quinolone antibacterial compounds. The ability of the nx naphthyridyl ring to interact with and inhibit some proteins has encouraged the investigation of similar structures in the search for more active compounds with less adverse effects. The possibility of structural modification by attachment of other biologically active moieties to the naphthyridyl ring of nx allowed the development of new active antimicrobial molecules. Hydrazone derivatives of nx can be synthesized easily based on the condensation of the hydrazide derivative of nx with the desired aldehyde or ketone. Only a few complexes with nx hydrazone derivatives have been described but for none were the crystal structures elucidated. The synthesis of a new one‐dimensional Cu^II coordination polymer, namely catena‐poly[[copper(II)‐di‐μ‐chlorido‐copper(II)‐{μ‐1‐ethyl‐N′‐[(1H‐imidazol‐4‐yl)methylidene]‐7‐methyl‐4‐oxo‐1,4‐dihydro‐1,8‐naphthyridine‐3‐carbohydrazidato}‐[dimethanolcopper(II)]‐{μ‐1‐ethyl‐N′‐[(1H‐imidazol‐3‐yl)methylidene]‐7‐methyl‐4‐oxo‐1,4‐dihydro‐1,8‐naphthyridine‐3‐carbohydrazidato}] dichloride methanol tetrasolvate], {[Cu₃(C₁₆H₁₅N₆O₂)₂Cl₂(CH₃OH)₂]Cl₂·4CH₃OH}_n, with the (1H‐imidazol‐4‐yl)methylidene carbohydrazide derivative of nalidixic acid (denoted h4imi), is presented and its structure is compared to the density functional theory (DFT) optimized structure of free h4imi. The title structure presents an octahedral Cu^II ion on an inversion centre alternating along a polymer chain with a square‐pyramidal Cu^II ion, with the two Cu^II centres bridged by two chloride ligands. Hydrogen bonds involving chloride counter‐ions and methanol solvent molecules mediate the three‐dimensional packing of the polymer. Comparison of the geometrical results from the structure analysis with those derived from a DFT study of the free ligand reveal the differences that arise upon coordination.     

Copper(II) Halide Complexes with 1‐tert‐Butyl‐1H‐1,2,4‐triazole and 1‐tert‐Butyl‐1H‐tetrazole

1‐tert‐Butyl‐1H‐1,2,4‐triazole (tbtr) was found to react with copper(II) chloride or bromide to give the complexes [Cu(tbtr)₂X₂]_n and [Cu(tbtr)₄X₂] (X = Cl, Br). 1‐tert‐Butyl‐1H‐tetrazole (tbtt) reacts with copper(II) bromide resulting in the formation of the complex [Cu₃(tbtt)₆Br₆]. The obtained crystalline complexes as well as free ligand tbtr were characterized by elemental analysis, IR spectroscopy, thermal and X‐ray analyses. For free ligand tbtr, ¹H NMR and ¹³C NMR spectra were also recorded. In all the complexes, tbtr and tbtt act as monodentate ligands coordinated by Cu^II cations via the heteroring N⁴ atoms. The triazole complexes [Cu(tbtr)₂Cl₂]_n and [Cu(tbtr)₂Br₂]_n are isotypic, being 1D coordination polymers, formed at the expense of single halide bridges between neighboring copper(II) cations. The isotypic complexes [Cu(tbtr)₄Cl₂] and [Cu(tbtr)₄Br₂] reveal mononuclear centrosymmetric structure, with octahedral coordination of Cu^II cations. The tetrazole compound [Cu₃(tbtt)₆Br₆] is a linear trinuclear complex, in which neighboring copper(II) cations are linked by single bromide bridges.     

Synthesis and characterization of mononuclear copper(II) and dinuclear cadmium(II) complexes with di-(2-picolyl)sulfide

The reaction of CuCl₂ · 2H₂O and CdCl₂ with di-(2-picolyl)sulfide (dps) leads to the formation of mononuclear copper(II) and binuclear cadmium(II) complexes, [Cu(dps)Cl₂] · H₂O (1) and [(dps)(Cl)Cd^II(μ-Cl)₂Cd^II(Cl)(dps)] (2). The copper atom in (1) is coordinated to one sulfur and two nitrogen atoms from the dps ligand and two chlorides in a distorted square-pyramidal environment. Complex (2) has two distorted octahedra sharing the basal edge that contain the bridging chloro ligands, each of which resides at a center of inversion. Cyclic voltammetric data show that (1) undergoes two reversible one-electron waves corresponding to Cu^II/Cu^III and Cu^II/Cu^I processes. However, cyclic voltammetry of (2) gives two irreversible reduced waves.