Low-dimensional compounds containing cyano groups. III: a structural,spectral and thermal study of dicyanoargentates containing 4-methylpyridine

The complexes Cu^II(4-Mepy)₂Ag₂(CN)₄ (1) and Cu^II(4-Mepy)₃Ag_2–x Cu^I _x (CN)₄ (2) (4-Mepy = 4-methylpyridine, x = 0.07) were isolated from a reaction mixture containing 4-Mepy, K[Ag(CN)₂] and CuSO₄. I.r. spectra indicated the presence of both monodentate and bridging cyano groups in (1) and (2), confirmed by their known structures, both consisting of neutral zigzag chains. Two neighbouring chains in (2) are linked by argentophilic interactions between Ag atoms of bridging dicyanoargentate anions, whose positions are partly occupied by Cu^I ions to the extent of 7 at.%, with an unusually short Ag...Ag distance of 2.9264(5) Å, to form a ladder. Individual ladders are tied together as sheets by weaker argentophilic interactions between silver atoms of interdigitated monodentate dicyanoargentate anions of two different ladders. Thermal decomposition of (2) occurs in two separated stages. In the first stage, three 4-Mepy molecules are liberated from the formula unit and, in the second stage, redox decomposition of the cyano groups occurs. The thermal decomposition of (1) is more complicated as the release of two 4-Mepy molecules is overlapped by decomposition of one cyano group followed by further redox decomposition of the remaining cyano groups.     

Low‐dimensional compounds containing cyano groups. XII.)copper(II) perchlorate

The title compound, [Cu(C₂N₃)(C₃H₁₀N₂)₂]ClO₄, is made up of [Cu(tn)₂{N(CN)₂}]⁺ complex cations (tn is 1,3‐diamino­propane) and ClO₄⁻ anions. The Cu^II atom is coordinated by four N atoms of two equatorial tn ligands, with an average distance of 2.041 (7) Å, and one nitrile N atom of the dicyanamide anion in an axial position, at a distance of 2.236 (3) Å, in a manner approaching square‐planar coordination geometry. The complex has C_s symmetry, with the mirror plane lying through the central C atoms of both tn ligands and the dca ligand. The ClO₄⁻ anion might be considered as very weakly coordinated in the opposite axial position [Cu—O = 2.705 (3) Å], thus completing the Cu^II coordination to asymmetric elongated octa­hedral (4+1+1*). The Cu atom and the perchlorate anion both lie on mirror planes.     

Synthesis,crystal structure,DNA binding,and oxidative cleavage activity of copper(II)-bipyridyl complexes containing tetraalkylammonium groups

Two copper(II) complexes of disubstituted 2,2′-bipyridine (bpy = 2, 2′-bipyridine) with tetraalkylammonium groups, [Cu(L¹)₂Br](ClO₄)₅·2H₂O (1) and [Cu(L²)₂Br](ClO₄)₅·H₂O (2) (L¹ = [4, 4′-(Et₃NCH₂)₂-bpy]²⁺, L² = [4, 4′-((n-Bu)₃NCH₂)₂-bpy]²⁺), have been synthesized and characterized. X-ray crystallographic study of 1 indicates that Cu(II) is a distorted trigonal bipyramidal or square pyramid. DNA binding of both complexes was studied by UV spectroscopic titration. In the presence of reducing reagents, the cleavage of plasmid pBR322 DNA mediated by both complexes was investigated and efficient oxidative cleavage of DNA was observed. Mechanistic study with reactive oxygen scavengers indicates that hydrogen peroxide and singlet oxygen participate in DNA cleavage.     

Synthesis,spectral and magnetic properties of binuclear copper(II)/nickel(II) and copper(II) complexes bridged by glyoximate groups

Three new dinuclear complexes, [(tmen) (H2O)2Ni (Hdmg)(dmg)Cu]·ClO4, [(dien)(H2O)Ni (Hdmg)(dmg) Cu]·ClO4 and [(tmen)Cu(Hdmg)(dmg) Cu] ClO4·H2O (H2dmg=dimethylglyoxime, tmen=tetramethylene diamine), have been prepared. Variable-temperature- magnetic susceptibility measurements (75–300K) on the complexes reveal the presence of intramolecular antiferromagnetic interactions through the oximate bridges. The formation of mononuclear, dinuclear complexes has been confirmed by spectrophotometry.     

New trinuclear carbonato-bridged copper(II) complexes: Synthesis,crystal structure,and spectroscopic properties

New trinuclear carbonato-bridged copper(II) complexes, [Cu₃(Bipy)₆(μ₃-CO₃)](CF₃SO₃)₄(H₂O)_0.5 (I) and [Cu₃(Phen)₆(μ₃-CO₃)](CF₃SO₃)₄(H₂O)_0.5 (II) (Bipy = 2,2′-bipyridine and Phen = 1,10-phenanthroline), have been synthesized and characterized by X-ray crystallography. In the trinuclear units, a carbonate anion triply bridges three Cu atoms in a μ₃-η¹:η¹:η¹-CO₃ mode. The environment around each copper(II) center is five-coordinate ranging between intermediate to distorted square-pyramidal geometry. In the crystal packing, the molecule of I is involved in a variety of intra/intermolecular non-covalent interactions such as intra/intermolecular stacking and CH···π interactions between the pyridine groups of the chelated ligand, leading to a one-dimensional arrangement of I. In complex II, the molecule is involved in both intra- and intermolecular Phen-Phen π-stacking, forming a three-dimensional network. The spectroscopic (IR, diffuse reflectance, and EPR spectra) properties and the preliminary results of magnetic measurements of both complexes are investigated and compared to other closely related trinuclear copper(II) complexes.     

Synthesis,structure, spectra and redox chemistry of mono- and dinuclear copper(II) complexes containing pyridyl groups

Copper(II) complexes generalized as Cu₂N₆ and CuN₆ were prepared by using hexadentate ligands, and their spectral and electrochemical behavior was analysed. X-ray analysis of binuclear [Cu₂L²Cl₂]²⁺ reveals that one copper is trigonal bipyramidal and the other is square pyramidal. Electronic spectra used to determine their stereochemistry in solution indicate that dinuclear Cu₂N₆ has two visible bands that correspond to a typical five-coordinate copper(II) environment, whereas only one broad band was obtained for mononuclear CuN₆. When NaN₃ was added to the dinuclear compounds, their UV–visible spectra underwent significant changes and an isosbestic point at 650?nm was observed; however, no such feature was encountered for the mononuclear compounds.     

The structure,magnetic and spectral properties of 4-acetylpyridine N-oxide complexes of copper(II) propionates

The synthesis and characterization of CuX₂L; (X = CH₃CH₂COO^?, ClCH₂CH₂COO^?, CH₃CHClCOO^? or CH₃CCl₂COO^?; and L = 4-acetylpyridine N-oxide) is reported. The characterization of these compounds was based on electronic, infrared and EPR spectra, as well as magnetic measurements over the temperature range. Several correlations between the spectral and magnetic data as well as pK_a values of the respective acids were found and discussed. On the basis of spectral and magnetic data the structures of the compounds are discussed.     

Synthesis,crystal structure and physicochemical properties of copper(II) complexes containing bis[(benzimidazol-2-yl)methyl] ether derivatives

A new benzimidazoyl ligand bis[(N-ethylbenzimidazol-2-yl)methyl]ether (EDGB) and Cu^II complexes [Cu(L¹) (L²)](ClO₄)·mEt₂O·nH₂O [L¹ = bis[(benzimidazol-2-yl)methyl]ether (DGB) or EDGB, L² = 2,2-bipyridine (bipy) or 1,10-phenanthroline (phen)] have been synthesized and characterized by elemental analyses and i.r. spectra. The single-crystal structure of the [Cu(phen)(DGB)(OClO₃)]ClO₄·Et₂O·0.5H₂O complex was determined by X-ray diffraction. The geometry around Cu is best described as a distorted octahedron with four nitrogen atoms from phen and DGB ligands forming the equatorial plane. The oxygen atoms of DGB and one perchlorate group are in the axial positions with semi-coordinated bonding modes. The electrochemical behavior of the complexes is described.     

Synthesis, spectral characterization and crystal structure of copper(II) complexes of 2-benzoylpyridine-N(4)-phenylsemicarbazone

An interesting series of nine new copper(II) complexes [Cu₂L₂(OAc)₂]·H₂O (1), [CuLNCS]·½H₂O (2), [CuLNO₃]·½H₂O (3), [Cu(HL)Cl₂]·H₂O (4), [Cu₂(HL)₂(SO₄)₂]·4H₂O (5), [CuLClO₄]·½H₂O (6), [CuLBr]·2H₂O (7), [CuL₂]·H₂O (8) and [CuLN₃]·CH₃OH (9) of 2-benzoylpyridine-N(4)-phenyl semicarbazone (HL) have been synthesized and physico-chemically characterized. The tridentate character of the semicarbazone is inferred from IR spectra. Based on the EPR studies, spin Hamiltonian and bonding parameters have been calculated. The g values, calculated for all the complexes in frozen DMF, indicate the presence of the unpaired electron in the d_x²-y² orbital. The structure of the compound, [Cu₂L₂(OAc)₂] (1a) has been resolved using single crystal X-ray diffraction studies. The crystal structure revealed monoclinic space group P2₁/n. The coordination geometry about the copper(II) in 1a is distorted square pyramidal with one pyridine nitrogen atom, the imino nitrogen, enolate oxygen and acetate oxygen in the basal plane, an acetate oxygen form adjacent moiety occupies the apical position, serving as a bridge to form a centrosymmetric dimeric structure.     

Synthesis,crystal structure,and in vitro antitumor activities of copper(II) complexes containing tetradentate pyridine-based ligands

Several new Cu(II) complexes of Schiff bases obtained by condensation of 2-[N-(α-picolyl)-amino]-benzophenone with different chiral amino acids were synthesized and characterized by physico-chemical and spectroscopic methods. The crystal structure of one of the complexes was determined using single crystal X-ray diffraction. The ligands were coordinated to the metal atom in a tetradentate manner with ONNN donor sets using the carboxyl oxygen, azomethine nitrogen, CON⁻, and pyridine nitrogen. The cytotoxicities of the complexes were evaluated against human cancer cells. The substituents on the aromatic rings strongly influenced the cytotoxicities of the complexes. The complex with bromine substituents on the pyridine rings showed the highest cytotoxicity. The antitumor activities against tumor cell lines were assayed in vitro, and the complexes were found to be highly effective, with six of the nine complexes having inhibition ratios better than that of 5-Fluorouracil. This behavior is indicative of a high ability to circumvent the cellular drug resistance mechanisms.     

Synthesis, crystal structures and magnetic properties of tricyanomethanide-containing copper(II) complexes

The preparation, crystal structures and magnetic properties of the copper(II) complexes of formula [Cu(pyim)(tcm)(2)](n) (1), [Cu(bpy)(tcm)(2)](n) (2), [Cu(4)(bpz)(4)(tcm)(8)] (3), {[Cu(terpy)(tcm)].tcm}(n) (4) and {[Cu(2)(tppz)(tcm)(4)].3/2H(2)O}(n) (5) [pyim = 2-(2-pyridyl)imidazole, tcm = tricyanomethanide, bpy = 2,2'-bipyridine, bpz = 2,2'-bipyrazine, terpy = 2,2':6',2'-terpyridine and tppz = 2,3,5,6-tetrakis(2-pyridyl)pyrazine] are reported. Complexes, 1, 2 and 4 are uniform copper(II) chains with single- (1 and 4) and double-(2) micro-1,5-tcm bridges with values of the intrachain copper-copper separation of 7.489(1) (1), 7.520(1) and 7.758(1) (2) and 7.469(1) A (4). Each copper atom in 1, 2 and 4 is five-coordinate with bidentate pyim (1)/bpy (2) and tridentate terpy (4) ligands and nitrile-nitrogen atoms from bridging (1,2 and 4) and terminal (1) tcm groups building a distorted square pyramidal surrounding. The structure of 3 is made up of neutral centrosymmetric rectangles of (2,2'-bipyrazine)copper(II) units at the corners, the edges being built by single- and double-micro-1,5-tcm bridges with copper-copper separations of 7.969(1) and 7.270(1) A, respectively. Five- and six-coordinated copper atoms with distorted square pyramidal and elongated octahedral environments occur in . Compound 5 is a neutral copper(II) chain with regular alternating bis-tridentate tppz and double micro-1,5-tcm bridges, the intrachain copper-copper distances being 6.549(7) and 7.668(1) A, respectively. The two crystallographically independent copper atoms in 5 have an elongated octahedral geometry with three tppz nitrogen atoms and a nitrile-nitrogen atom from a bridging tcm group in the equatorial positions, and two nitrile nitrogen atoms from a terminal and a bridging tcm ligand occupying the axial sites. The investigation of the magnetic properies of 1-5 in the temperature range 1.9-295 K has shown the occurrence of weak ferro- [J = +0.11(1) cm(-1) (2)] and antiferromagnetic interactions [J = -0.093(1) (1), -0.083(1) (4), -0.04(1) and 1.21(1) cm(-1) (3)] across the micro-1,5-tcm bridges and intermediate antiferromagnetic coupling [-J = 37.4(1) cm(-1) (5)] through bis-tridentate tppz. The values of the magnetic interactions are analyzed through simple orbital symmetry considerations and compared with those previously reported for related systems.     

Synthesis,spectral characterization and crystal structure of copper(II) complexes of 2-hydroxyacetophenone-N(4)-phenyl semicarbazone

Six new copper(II) complexes of 2-hydroxyacetophenone-N(4)-phenyl semicarbazone have been synthesized and physico-chemically characterized. The tridentate character of the semicarbazone is inferred from IR spectra. Based on EPR studies, the spin Hamiltonian and bonding parameters have been calculated. The g   values, calculated for all the complexes in frozen DMF, indicate the presence of the unpaired electron in the d_x2-y2${\text{d}}_{x^2-y^2}$ orbital. The metal–ligand bonding parameters evaluated showed strong in-plane σ and in-plane π-bonding. The structure of the compound, CuLphen has been resolved using single crystal X-ray diffraction studies. The crystal structure revealed a monoclinic lattice with space group symmetry P2₁/c. The compound adopts a distorted square pyramidal geometry with a N₂O₂ core as the base.     

Two copper(II) complexes with 4-benzoylpyridine ligand: synthesis, crystal structure and luminescent properties

Two new copper(II) complexes Cu(NCS)2(4-Bzpy)2 (1) and Cu(NO3)2(4-Bzpy)4 (2) (4-Bzpy=4-benzoylpyridine) have been synthesized and characterized by IR, UV, elemental analysis and X-ray crystallography. Cu(II) atom has a square planar environment for 1 and an distorted octahedral environment for 2, respectively. In solid state there are C-H?π interactions and C-H?S hydrogen bonds between adjacent molecules in complex 1. The molecule of complex 2 is further connected by multiform π-π interactions, C-H?π interactions and C-H?O hydrogen bonds to form a three-dimensional supramolecular structure. The luminescent properties of the complexes 1 and 2 were both investigated in H2O solution and in solid state at room temperature, respectively.     

Synthesis,characterization, crystal structure,and electrochemical properties of three copper(II) complexes with 3,5-dihalosalicylaldehyde Schiff bases derived from amantadine

Abstract

Complexes 1-3, C₃₄H₃₆X₄CuN₂O₂ (X?=?Cl, Br, I), were synthesized with copper chloride dihydrate and three new Schiff base ligands derived from amantadine and 3,5-dihalosalicylaldehydes. They were characterized by IR, UV–VIS, elemental analysis, molar conductance, and single-crystal X-ray diffraction. Single-crystal X-ray diffraction analysis reveals that 1 and 2 crystallize in the triclinic system, Pī space group. Each asymmetric unit consists of one copper(II) ion, two corresponding deprotonated Schiff base ligands and one lattice dichloromethane molecule. 3 crystallizes in the monoclinic system, P2₁/n space group. Each asymmetric unit consists of one copper(II) ion and two deprotonated iodo- Schiff base ligands. The tetra-coordination of the central copper(II) ion in 1-3 is constructed by two nitrogen atoms and two oxygen atoms from the corresponding Schiff base ligands, forming a distorted tetrahedral geometry. Electrochemical properties of the complexes were determined by cyclic voltammetry.

     

Synthesis, characterization and structures of copper(II) complexes containing carboxylate and sulfonate groups

Four copper(II) complexes containing Schiff base and reduced Schiff base ligands derived from pyridine-2-aldehyde and amino acid containing carboxylate and sulfonate functional groups (N-(2-pyridylmethylene)-amino acid and N-(2-pyridylmethyl)-amino acid, (amino acids = ??-alanine and aminoethanesulfonic acid) namely, [Cu(Pbals)(H₂O)₂]ClO₄·H₂O 1, [Cu(Pbal)(ClO₄)(H₂O)] 2, [Cu₂(Paes)₂(ClO₄)₂]·2H₂O 3, and [Cu(Pae)(H₂O)]·ClO₄·H₂O 4 have been synthesized and characterized. The structural features of carboxylate and sulfonate donor groups have been elucidated. These copper(II) complexes demonstrate different coordination behaviour of the carboxylate and sulfonate groups. Carboxylate groups in complexes 1 and 2 bridge the metal centers and facilitate the formation of 1D helical coordination polymeric structures. In compound 3, the sulfonate groups bridge the metal centers to form a discrete dinuclear complex. In 4, the sulfonate groups link the neighbouring metal centers to form a 1D coordination polymeric structure.     

Hybrid inorganic-metalorganic compounds containing copper(II)-monosubstituted Keggin polyanions and polymeric copper(I) complexes

Four hybrid inorganic-metalorganic compounds containing copper(II)-monosubstituted Keggin polyoxotungstates, K3[Cu(I)(4,4'-bpy)]3[SiW11Cu(II)O39].11H2O (1), (paraquat)3[SiW11Cu(II)O39].6H2O (2; paraquat = N,N'-dimethyl-4,4'-bipyridinium), K3[Cu(I)(4,4'-bpy)]3[GeW11Cu(II)O39].11H2O (3), and Na2[Cu(I)(4,4'-bpy)]3[PW11Cu(II)O39(H2O)].4H2O (4), have been synthesized under autogenous pressure hydrothermal conditions and characterized by elemental analysis and infrared spectroscopy (FT-IR). The crystal structures of 1, 2, and 4 have been established by single-crystal X-ray diffraction. The crystal packings are characterized by the presence of monodimensional extended entities: either the polymeric polyanion [SiW11CuO39]n(6n-) (2), the cationic [Cu(4,4'-bpy)]n(n+) chain (4), or both simultaneously as in compound 1, where the inorganic and metalorganic sublattices are mutually perpendicular. To asses the influence of packing in the copper(I) complex structural diversity found in compounds 1 and 4, a search in the CSD database has been performed and the resulting geometrical features have been analyzed and compared with experimental crystallographic data and DFT calculations.     

Synthesis,spectral, magnetic and electrochemical properties of new dimeric copper(II) complexes

Four new ligands, bis-[3,5-disubstituted-2-hydroxybenzyl]-N-alkylamines (L¹–L⁴) with three potential donor sites, capable of forming dimeric copper(II) complexes have been prepared. The dimeric nature of the complexes has been confirmed by FAB mass spectral studies. Molar conductance studies indicate that the complexes are neutral. Electrochemical studies indicate that the complexes undergo quasi reversible two step single electron transfers at negative potentials (E_pc¹=−0.34 to −0.48 V, E_pc²=−0.59 to −0.72 V). Variable temperature magnetic studies indicate that the complexes are antiferromagnetically coupled (−2J=290 to 400 cm⁻¹). ESR spectral studies in DMF indicate that the complexes are dimeric and undergo dissociation on addition of pyridine.     

Preparation and characterization of diruthenium(II,III) compounds containing terminal olefin groups

4-Vinylbenzoic acid reacted with Ru₂(D(3,5-Cl₂Ph)F)₃(OAc)Cl and cis-Ru₂(D(3,5-Cl₂Ph)F)₂(OAc)₂Cl (D(3,5-Cl₂Ph)F is N,N′-bis(3,5-dichlorophenyl)formamidinate) to yield Ru₂(D(3,5-Cl₂Ph)F)₃(4-vinylbenzoate)Cl (1) and cis-Ru₂(D(3,5-Cl₂Ph)F)₂(4-vinylbenzoate)₂Cl (2), respectively. Ru₂(D(3,5-Cl₂Ph)F)₃(OAc)Cl reacted with 5-hexenoic acid and 6-heptenoic acid to afford Ru₂(D(3,5-Cl₂Ph)F)₃(5-hexenoate)Cl (3) and Ru₂(D(3,5-Cl₂Ph)F)₃(6-heptenoate)Cl (4), respectively. All new compounds were characterized using voltammetric and Vis–NIR spectroscopic techniques, and the structures of 1 and 2 were also established through X-ray single crystal diffractions.     

Crystal structure of copper(II) cimetidine sulphate nonahydrate. Cation distortion and structure isomerism in three copper(II) cimetidine complexes

In the crystalline state, the complex [Cu(CM)₂]SO₄·9H₂O (CM = cimetidine) is constituted of two-dimensional cations[Cu(CM)₂²⁺]_n separated by SO₄²⁻ anions and water molecules. As in the related complexes [Cu(CM)₂](ClO₄)₂ and [Cu(CM)₂](NO₃)₂, the copper atom lies in a strongly distorted octahedral CuN₄S₂ environment. The distortion is quite different from one complex to another (cation distortion isomerism). In the title compound the CuS bond is unusually long (2.91 Å). Unlike the title compound, the [Cu(CM)₂²⁺]_n cations in the perchlorate and nitrate salts are one-dimensional infinite chains characterized by different conformations of the cimetidine molecules (cation structure isomerism).