Verfeinerung der Kristallstruktur von Kupfer(II)-hydroxichlorid,Cu(OH)Cl

The crystal structure of Cu(OH)Cl [a=5.555 (2) Å,b=6.671 (4) Å,c=6.127 (2) Å, =114.88 (3)°, space group P2_I/a,Z=4] was refined for 810 observed reflections with sin /0.80 Å^–1 toR=0.035. Crystals were synthesized under hydrothermal conditions. The copper atom is planar four coordinated by three oxygen atoms and one chlorine atom; two further chlorine atoms complete its coordination. The copper polyhedra share edges to build up sheets, which are connected by hydrogen bonds to the chlorine atoms of adjacent sheets.

     

Self-assembling dicopper(II) complexes of di-2-pyridyl ketone Schiff base ligands derived from S-alkyldithiocarbazates

Condensation of di-2-pyridyl ketone with S-methyldithiocarbazate or S-benzyldithiocarbazate yields potentially bridging ligands of the form Py₂CNNHC(S)SR; Hdpksme (R = Me; the di-2-pyridyl ketone Schiff base of S-methyldithiocarbazate) and Hdpksbz (R = Bz; the di-2-pyridyl ketone Schiff base of S-benzyldithiocarbazate). Complexation of these ligands with Cu(II) in a 1:1 M ratio leads to the formation of dinuclear complexes of the general formula [Cu(NNNS)X]₂ (X = Cl⁻, NO₃⁻, H₂O). X-ray crystallographic structure determinations show that each ligand provides three donor atoms (NNS) in a meridional configuration to one metal, viz. one of the pyridine nitrogen atoms, the azomethine nitrogen atom and the thiolate sulfur, while the nitrogen atom of the second pyridyl group forms a bridge to another copper(II) ion within the dimer. The coordination geometry around each copper(II) ion is approximately square pyramidal, the basal plane of which is composed of one of the pyridine nitrogen atoms, the azomethine nitrogen atom and a chlorido, nitrato or aqua ligand. The apical position of the square pyramid is always occupied by the pyridine nitrogen atom of the second ligand.     

Coordination behaviour of Schiff base 2-acetyl-2-thiazoline hydrazone (ATH) towards cobalt(II), nickel(II) and copper(II)

The synthesis and characterization of Co(II), Ni(II) and Cu(II) complexes of 2-acetyl-2-thiazoline hydrazone (ATH) are reported. Elemental analysis, IR spectroscopy, UV–Vis–NIR diffuse reflectance and magnetic susceptibility measurement, as well as, in the case of copper complex EPR spectroscopy, have been used to characterize the complexes. In addition, the structure of [NiCl₂(ATH)₂] (2) and [{CuCl(ATH)}₂(μ-Cl)₂] (3) have been determined by single crystal X-ray diffraction. In all complexes, the ligand ATH bonds to the metal ion through the imine and thiazoline nitrogen atoms. X-ray data indicates that the environment around the nickel atom in 2 may be described as a distorted octahedral geometry with the metallic atom coordinated to two chlorine atoms, two thiazoline nitrogen atoms and two imino nitrogen atoms. With regard to 3, it can be said that its structure consists of dimeric molecules in which copper ions are bridge by two chlorine ligands. The geometry about each copper ion approximates to a distorted square pyramid with each copper atom coordinated to one thiazoline nitrogen atom, one imine nitrogen atom, one terminal chlorine ligand and two bridge chlorine ligands. In compound 3, magnetic susceptibility measurements in the temperature range 2–300 K show an intradimer antiferromagnetic interaction (J = −7.5 cm⁻¹).     

Influence of heterocycles arrangement in structural isomeric ligands on coordination sphere of copper(II) complexes: Crystal structures and spectroscopic characterization

New copper complexes with two structural isomeric ligands, 2-(indazol-1-yl)-2-thiazoline (TnInA) and 2-(indazol-2-yl)-2-thiazoline (TnInL), have been synthesized and characterized by magnetic measurements, IR, electronic and EPR spectroscopies. Moreover, the molecular structures of [Cu(NO₃)(TnInA)₂(H₂O)](NO₃) · (H₂O) (1) and [Cu(NO₃)₂(TnInL)(H₂O)] (2) have been resolved by single-crystal X-ray diffraction studies. In compound 1 the copper ion is in a distorted octahedral geometry, with the equatorial plane formed by four nitrogen donor atoms from two organic ligands and the axial positions occupied by two oxygen atoms from a water molecule and a mono-coordinated nitrate anion. The coordination geometry around the copper atom in compound 2 can be described basically as a square pyramid with two nitrogen atoms from TnInL ligand, one oxygen atom from a water molecule and one oxygen atom from a nitrate group in the equatorial plane. The axial position is occupied by one oxygen atom from a nitrate group. Likewise, a second oxygen atom from the last nitrate group in equatorial position might involve in a weak sixth coordination position to give a (4 + 1 + 1^∗) coordination mode.     

Structural features of the copper(II) chloride-triphenylphosphine-N-(2-pyrimidyl)imine complex in crystal and solution

The structure of the copper(II) chloride-triphenylphosphine-N-(2-pyrimidyl)imine complex in crystal and solution was investigated by x-ray analysis and EPR. It was found that despite the difference in the structures of the dissolved and crystalline complexes, the exocyclic nitrogen atom is contained in the coordination sphere of the metal together with the nitrogen atom of the heterocycle in both cases due to the electronic effect of the phosphorus atom. In the crystal, the copper atom is coordinated with two chlorine atoms and two molecules of the ligand, and the distance from the copper cation to the nitrogen atoms of the pyrimidine rings is significantly less than the distance to the nitrogen atoms of the phosphinimine groups (2.0 and 2.8 Å, respectively). The coordination polyhedron formed as a result is a strongly distorted axially asymmetric octahedron. In dissolution, the chlorine anions are substituted by molecules of the solvent, the complex acquires axial symmetry, and four nitrogen atoms from two ligands form a planar square with a copper(II) cation in the center.A. N. Nesmeyanov Institute of Organoelemental Compounds, Russian Academy of Sciences, 117813 Moscow. Translated from Izvestiya Akademii Nauk, Seriya Khimicheskaya, No. 1, pp. 118–125, January, 1992.     

Tetranuclear copper complexes with new β-diketone and β-iminoketone-containing ligands

Novel tetranuclear copper complexes, Cu4(OH)2(ClO4)3 (HA)·H2O (1) and Cu4(ClO4)5(H3B)·3H2O (2), were synthesized by reacting 1,5-bis(1-phenyl-3-methyl-5-pyrazolone-4)-1 ,5-pentanedione with 1,3-propanediamine and 2-hydroxyl-1,3-propanediamine in the presence of a template reagent copper ion. New [2+2] type open cyclic multidentate ligands are also obtained from the reaction (H4A and H6B stand for new compounds from 1,3-propanediamine and 2-hydroxyl-1,3-propanediamine, respectively). They each contain five C = O, three C = N and one NH2 groups. The complexes were characterized by elemental analyses, conductivity, FT-i.r. (micro-i.r., deconvolution technique), FAB-MS, e.s.r., electronic spectra and extended X-ray absorption fine structure (EXAFS). Copper ions in (1) are basically four coordinate with tetragonal geometry. The average coordination bond distances of Cu–N and Cu–O are 1.91 Å and 2.05 Å. In (2), copper ions are primarily five coordinate with square-based pyramidal geometry. The average coordination bond distances of Cu–N and Cu–O are 1.93Å and 2.08Å. Four copper atoms in molecules may be arranged tetragonally. Both the ligand field and the coordination bonds in complex (1) are stronger than those in (2). Investigations on variable temperature susceptibilities show that some antiferromagnetic exchange interaction exist in the complexes. The plots of –1 versus T obey the Curie-Weiss law only at low temperature. Preliminary results of a bioassay indicate that the two complexes have some antitumour activity in vitro.     

Synthesis and x-ray crystal structure of a dinuclear copper(I) thiobenzoate triphenylphosphine complex

Summary In 9,10-phenanthrenesemiquinonatobis(triphenylphosphine)copper(I) (1) the semiquione ligand is oxidized by dibenzoyl disulphide to 9,10-phenanthrenequinone and the complex [(PPh₃)Cu(-PhCOS)₂ Cu(PPh₃)₂] (3) is formed. Crystals of the complex are triclinic, space group , with cell parametersa=10.712(1),b=12.887(1).c=22.064 Å, =78.29(1), =81.88(1), =80.83(1), and Z=2. The copper atoms are bridged by the sulphur atoms of the two thiobenzoate groups to form binuclear molecules. The Cu₂S₂ rhombus is strictly co-planar (Cu–S distances from 2.309 to 2.424 Å). The trigonal planar co-ordination around the one and the tetrahedral coordination around the other copper atom are completed by the phosphorus atoms of the triphenylphosphine molecules (Cu–P distances from 2.238 to 2.287 Å). The copper-copper distance (Cu–Cu=2.620 Å) is 0.6 Å longer than that in metallic copper.     

Synthesis, crystal structure and DFT analysis of a new trinuclear complex of copper

The new trinuclear complex [Cu₂(μ-L)₂CuCl₂] has been synthesized and characterized by elemental analysis, IR, UV-Vis and X-ray spectroscopy, where L is a dianionic tetradentate Schiff base ligand with N₂O₂ donor atoms. The molecular structure of [Cu₂(μ-L)₂CuCl₂] was determined by X-ray crystallography. In the complex, the most remarkable aspect of the trinuclear complex is that it adopts a bent structure for the three copper atoms, with a Cu1Cu3Cu2 intramolecular angle of approximately 90.62(2)°. All three copper atoms are five coordinate, with a slightly distorted square pyramidal geometry. In the two terminals moieties, the basal plane of the square pyramidal is formed by two oxygen atoms and two nitrogen atoms of the Schiff base ligand, and the apical position at the Cu atom is occupied by the bridging Cl1 anion. The Cu1Cl1Cu2 angle is 110.51(5)°. The central copper atom also has a five-coordinate, slightly distorted square pyramidal geometry, with four phenolato oxygens belonging to the Schiff base ligands from Cu(salpn) units describing the square planar base and the Cl anions being apical. The optimized structure of the complex has been studied using the B3LYP/6-31G(d)/LanL2TZf level of theory. The calculation shows that all the copper atoms are five coordinate with distorted square pyramidal structures, which is consistent with experimental data.     

Copper(II) Cyanoacetate Polymer: Synthesis and Structure

A new copper carboxylate polymer with cyanoacetate anion as a ligand was synthesized and studied using X-ray diffraction, IR, and EPR spectroscopy. The crystal is tetragonal: a= 14.702(2) Å, c= 13.470(3) Å, Z= 8, space group I4₁/a, and R= 0.0634. The copper atoms in the centrosymmetric dimeric fragment have a square-pyramidal surrounding with the CuO₄N coordination core and are joined through four bidentate bridging anions of cyanoacetic acid Cu(1)"–O(1A) 1.931(4) Å, Cu(1)"–O(1B) 1.926(4) Å, Cu(1)–O(2B) 2.018(3) Å, Cu(1)–O(2A) 2.036(4) Å, and Cu(1)–N(1A)" 2.206(5) Å). The Cu···Cu" distance in the dimer is 2.709 Å. The copper atom is extended from the mean equatorial plane toward the axial nitrogen atom by 0.23 Å. EPR data confirm strong antiferromagnetic interaction (2J –275 cm^–1) between the copper(II) ions of the dimeric fragment, whereas the interaction between the dimers is significantly weaker (J< 0.3 cm^–1).     

Molecular structures and solid-solid phase transitions of trinuclear CpCo[P(O)(OR)2]3 2M complexes

Summary The trinuclear complexes {CpCo[P(O)(OMe)₂]₃}₂Co and {CpCo[P(O)(OEt)₂]₃}₂M, where M=Mg, Ca, Sr, Ba, Pb, Mn, Co, Ni, Cu, Zn, Cd or Hg, have been studied by x-ray diffraction methods and the crystal structures of {CpCo[P(O)(OR)₂]₃}₂M [R=Me with M=Co (1) and R = Et with M = Cu (2)] have been solved by the heavy atom technique. Complex (2) crystallizes in the triclinic space group P 1 with two crystallographically independent molecules per unit cell. The cell dimensions area = 12.195(3) Å,b = 20.429(6) Å, c = 12.518(3) Å, = 102.39(2)°, =120.15(2)°, =92.28(2)°. The molecule contains two cobalt atoms and one copper atom in a linear arrangement with copper situated on a center of symmetry. Each of the cobalt atoms is bonded to a cyclopentadienyl ring and is connected to the central copper atom by three phosphonate groups acting as bridging ligands. Disorder phenomena within these phosphonate groups are best described as an enhanced thermal motion corresponding mainly to a rotation around the Co-Cu-Co axis. The CuO₆ coordination octahedra exhibit a small (4+2) distortion.The electronic spectrum of this copper complex has been measured in solution and in the solid state and is in accord with the Jahn-Teller distorted octahedral coordination of the copper ion found in the x-ray structure.Complex (1) is monoclinic, space group P2₁/c with two formula units per cell. Its molecular structure shows the same general features as the copper complex. The coordination of the central cobalt atom is regularly octahedral within the limits of error. Parts of the phosphonate P(O)(OMe)₂ groups are disordered over two distinct sites in the crystal with occupancy factors ofca. 0.75 and 0.25.D.s.c. measurements of the trinuclear compounds containing disordered P(O)(OEt)₂ groups show phase transitions occurring in the 160–230 K temperature range that are best discussed in terms of order-disorder transitions. From d.s.c. measurements of the corresponding complexes with P(O)(OMe)₂ ligands, there are no phase transitions visible in the 100–300 K range.     

Structural researches on metal complexes with ligands containing the pyridoxal moiety: X-ray structure of chloro(N-pyridoxylidene-N′-salicyloylhydrazinato) copper(II) Monohydrate

Summary The x-ray crystal structure of the title complex is described Crystals are monoclinic, space groupP2₁/n, with unit-cell dimensions:a=18.070(2),b=13.471(2),c=6.788(2) Å,=94.70(1),Z=4. The structure was solved from diffractometer data by Patterson and Fourier methods and refined by least-squares techniques toR=5.0% for 2451 independent reflections. It consists of complex molecules, in which the copper atom square planar coordination comprises the chlorine atom, Cu-Cl=2.240(3) Å, and the organic ligand which acts as terdentate through the oxygen atom [Cu-O=1.948(3) Å] and a nitrogen atom, [Cu-N=1.933(5) Å] from the hydrazidic chain and the oxygen atom, [Cu-O = 1.894(4) Å] from the pyridoxal group.     

Copper(II) bromide complexes with acyclic and cyclic pyrimidine-containing phane ligands

Complexes of copper(II) bromide with cyclic and isostructural acyclic phane ligands containing derivatives of pyrimidine nucleobases (cytosine and uracil) were synthesized and characterized. In two cyclic pyrimidinophanes used, the macrocycles included two 6-methylthiocytosine and one 6-methyluracil units linked by polymethylene chains (L³) and two 6-methyluracil units linked by N-containing bridges (L⁵). Ligand L³ and its isostructural acyclic analogs are coordinated by the Cu²⁺ ion through the same donor sites (the ring N atoms of the thiocytosine units). The coordination polyhedra of the Cu atom in complexes with cyclic and acyclic ligands are different. Ligand L⁵ and its isostructural acyclic analog also form copper(II) complexes with different coordination polyhedra involving different donor sites. The acyclic ligand is coordinated by the Cu²⁺ ion via the bridging N atom, while cyclic ligand L⁵, via the uracil CO groups (the bridging N atoms become protonated). The resulting complexes are dielectrics.     

N,N′-dialkylsubstituted Imidazolidine-2-thionecopper(I) complexes. X-ray analysis of chloro-bis(N,N′-dimethylimidazolidine-2-thione)copper(I)

Summary New complexes of copper(I) withN,N-dialkylsubstituted imidazolidine-2-thione ligands were prepared by reduction of CuX₂ (X = Cl or Br). The i.r. spectra show that in all the complexes the ligand coordinates through the sulphur atom. The crystal structure of chloro-bis(N,N-dimethylimidazolidine-2-thione)copper(I) has been determined from x-ray diffraction data. Crystals are monoclinic. space groupC ₂, with unit cell dimensions:a = 16.022(15),b = 9.942(10),c = 15.112(15) A, = 139.84(10)², Z = 4. The final R index is 5.2%. The copper coordination is trigonal, involving sulphur atoms of the two ligands and One chlorine atom. The steric effect of the two methyls imposes a rotation of the imidazolidine rings with respect to the coordination plane. The dihedral angle between the mean plane of thiourea moieties. parallel one with the other. and the coordination plane is 119.3°.This work was supported by the National Research Council (C.N.R.) of Rome.     

Influence of Hydrogen Bonding in the Structure of Mixed-Ligand Copper(II) Chelates. Spectra and Structure of [Aquo((2,2′-Dipyridylamine)-(3-Chloro-2,4-Pentanedionato)Copper(II)] Nitrate

The IR, the ligand field spectra and the crystal structure of the mixed-ligand compound [(aquo)2,2-dipyridylamine(3-chloro-2,4-pentanedionato)copper(II)] nitrate, [Cu(dpyamH) Cl-acac(H₂O)]NO₃], are reported. The copper atom exists in a square pyramidal environment with the apical position occupied by the aqua ligand. The nitrogenous base and the -dionato anion act as bidentate ligands forming six-membered chelate rings. In addition to the coulombic interactions with the metal centre, the planar NO ₃ ^- group participates in specific electrostatic interactions involving the hydrogen atoms of the coordinated water molecule. The chlorine and the nitrogen atoms are also involved in hydrogen bonding. The structure of the compound was determined by single crystal X-ray diffraction analysis (triclinic, space group , a = 8.718(5), b = 9.407(5), c = 13.484 (7) Å, = 94.17(4)°, = 105.12(5)°, = 119.75(5)°, Z = 2, R = 0.0332, R _W = 0.0869).     

Metal–thiosemicarbazone interactions. Synthesis of an iodo-bridged dinuclear [diiodobis(pyrrole-2-carbaldehydethiosemicarbazone)dicopper(I)] complex

Reaction of copper(I) iodide with pyrrole-2-carbaldehydethiosemicarbazone (Hptsc) in a 1:1 mole ratio in MeCN, followed by addition of one mole of Ph₃P, yielded a complex of empirical formula, CuI(Hptsc)(Ph₃P), whose X-ray structure determination has shown that it exists as an iodo-bridged dinuclear copper(I) complex, [Cu₂(-I)₂( ¹-S-Hptsc)₂(PPh₃)₂](1). The central kernel, Cu(-I)₂Cu forms a parallelogram with unequal Cu—I distances {Cu—I, 2.644(2), 2.707(2)Å} and bond angles {Cu—I—Cu, 70.72(7), I—Cu—I, 109.28(7)°}. Each Cu atom is further bonded to one S atom of Hptsc and one P atom of Ph₃P, thus completing tetracoordination. The Cu...Cu separation of 3.097(4)Å is close to the sum of the van der Waals radius of the Cu atom, 2.80 Å. Compound (1) involves relatively strong inter-dimer hydrogen bonding via hydrazinic and pyrrole ring hydrogens with sulfur and iodine atoms respectively of the adjacent dimer {N(1)H...S^#2, 2.50 Å; N(4)H...I^#3, 2.91 Å}. The complex represents the first report of a copper(I) dimer with a thiosemicarbazone.     

Synthesis,spectral, thermal and structural characterization of {[Cu(H2O)3][Cu(MAL)2] · 2H2O}∞ and [Cu(MAL)(TEA)] · H2O (MAL = malonate and TEA = triethanolamine)

A polymeric malonato-bridged copper(II) complex, {[Cu(H₂O)₃][Cu(MAL)₂]· 2H₂O}, and a mononuclear malonato-copper(II) complex with triethanolamine, [Cu(MAL)(TEA)]·H₂O, have been prepared and characterized by elemental analyses, i.r., u.v.–vis, magnetic measurements and single crystal X-ray diffraction. The polymeric complex consists of one-dimensional chains containing the MAL bridged [Cu(H₂O)₃]²⁺ and [Cu(MAL)₂]^2– ions and each MAL ligand simultaneously exhibits chelating bidentate (at one copper atom) and bridging (at the adjacent copper atom) coordination modes. The intrachain Cu1...Cu2 separation is 4.963 Å and the polymeric complex exhibits antiferromagnetic behaviour. In the mononuclear complex, the copper(II) ion is octahedrally coordinated by one bidentate MAL and one tetradentate neutral TEA ligands. The i.r. spectra and thermal decompositions of both complexes are described.     

Crystal structure and spectroscopic study of di-μ(1,1)-azido-di-μ(0,0-nitrato)tetrakis(3,5-lutidine)dicopper(II), [Cu(N3) (NO3) (3,5-lutidine)2]2

A mixed ligand 12 complex of copper(II) azide with 3,5-lutidine, namely di-(1,1)-azido-di(0,0)-nitrato)tetrakis(3,5-lutidine)dicopper(II) has been prepared and characterized by X-ray crystallographic and spectroscopic methods. The dimeric molecule, which possesses a crystallographic inversion center, contains two(1,1) bridging azido ligands. Each copper(II) atom in the cyclic Cu₂N₂ unit is further coordinated by two oxygen atoms from two(0,0-nitrato) bridges at Cu-O distances of 2.465(3) and 2.568(3) Å and two nitrogen atoms from the lutidine molecules [Cu-N=2.003(3) and 2.012(3) Å] to give a distorted tetragonal bipyramid. Both azido ligands are linear [N-N-N angle=179.0(4) and asymmetric N-N=1.207(4) and N-N=1.135(5) Å]. The azido bridges produce a rather short Cu Cu distance of 3.013(2) Å. Infrared and electronic data are presented and discussed.     

Ferromagnetic exchange coupling in a new bis(μ-chloro)-bridged copper(II) Schiff base complex: Synthesis,structure, magnetic properties and catalytic oxidation of cycloalkanes

A new (μ-chloro)-bridged complex [Cu(HL)Cl]₂ · H₂O (1) with the Schiff base ligand H₂L, [2-((E)-(2-hydroxyethylimino)methyl)-4-bromophenol], has been synthesized and characterized by elemental analysis, IR, UV–Vis and EPR spectroscopic studies. X-ray diffraction studies show that 1 is a binuclear Cu^II complex with a pair of chlorine atoms bridging the copper atoms in a central Cu₂Cl₂ core. Each copper atom in 1 adopts a distorted square-pyramidal geometry with the imine nitrogen atom, alkoxy and phenoxy oxygen atoms from the Schiff base ligand and a bridging chlorine atom constructing the basal plane, while the apical position of the pyramid is occupied by the other bridging chlorine atom. Variable temperature susceptibility measurements show that complex 1 presents the highest ferromagnetic coupling [J = +43.2(5) cm⁻¹] reported till date in any doubly chloro-bridged Cu^II dimer, and a weak interdimer antiferromagnetic coupling [J′ = -0.276(8) cm⁻¹]. The complex also exhibits high catalytic activity towards the oxidation of hydrocarbons using H₂O₂ as terminal oxidant.     

Die Kristallstrukturen der Kupfer(II)-oxo-selenite Cu2O(SeO3) (kubisch und monoklin) und Cu4O(SeO3)3 (monoklin und triklin)

Syntheses within the system CuO-SeO₂-H₂O revealed four copper(II)-oxo-selenites. The crystal structures of these compounds were determined by single crystal X-ray techniques. Chemical formulae, lattice parameters and space groups are: Cu₂O(SeO₃)-I [a=8.925 (1) Å, P2₁3], Cu₂O(SeO₃)-II [a=6.987 (5) Å,b=5.953 (4) Å,c=8.429 (6) Å, =92.17 (3)°, P2₁/n], Cu₄O(SeO₃)₃-I [a=15.990 (8) Å,b=13.518 (8) Å,c=17.745 (12) Å, =90.49 (5)°, P2₁/a], and Cu₄O(SeO₃)₃-II [a=7.992 (6) Å,b=8.141 (6) Å,c=8.391 (6) Å, =77.34 (3)°, =65.56 (3)°, =81.36 (3)°, ].All the Cu atoms are-with one exception-[4], [4+1], and [4+2] coordinated by O atoms. The four nearest O atoms are more or less distorted square planar arranged. Within the CuO₄ squares the Cu-O bond lengths are significantly shorter for the [4] coordinated O atoms as compared with those of the [4+1] and [4+2] coordinated Cu atoms. The exception in the coordination of the Cu atoms is the Cu(1) atom in Cu₂O(SeO₃)-I with the site symmetry 3, which is trigonal dipyramidal [5] coordinated. A common feature of these four crystal structures is, that O atoms outside the SeO₃ groups are tetrahedrally coordinated by four Cu(II) atoms. The Se atoms are as usual [3] coordinated, building up SeO₃ pyramids. In all these four compounds the copper-oxygen polyhedra are combined to a three-dimensional network.

     

Synthesis,crystal structure and cyclic voltammetry of square- pyramidal acetatoaqua [(4-methylimidazol-5-yl)methylene] histamine copper(II) perchlorate

The copper atom in acetatoaqua[[(4-methylimidazol-5- yl)methylene]histamine]-copper(II) perchlorate (1) is N,N,N-chelated by the [(4-methylimidazol- 5-yl)methylene]histamine [Cu–N=1.969(3) 2.019(3) Å] donor ligand. The aqua ligand occupies the apical site of the square-pyramidal coordination polyhedron [Cu–O= 2.365(3) Å], whose fifth site is occupied by the carboxy oxygen atom of the monodentate acetato anion [Cu–O=1.960(3)Å]. Cyclic voltammetry in MeCN and N,N-dimethylformamide (DMF) gives a voltage of –0.39 and –0.37 V versus s.c.e, which compares well with the value obtained for Cu,Zn superoxide dimuthase itself.