Synthesis and characterisation of heterometallic trinuclear copper(II) and zinc(II) complexes derived from bis(2-hydroxy-1-naphthaldehyde)oxaloyldihydrazone

A new series of heterotrinuclear Cu(II)-Zn(II) complexes [ZnCu2(nph)(mu(2)-X)(2)(H2O)(6)] [X = Cl (1) and ClO4 (3)] and [ZnCu2(nph)(NO3)(2)(H2O)(6)]center dot H2O (2) have been synthesised from bis (2-hydroxy-1-naphthaldehyde)oxaloyldihydrazone and characterised. The stoichiometry of the complexes has been established on the basis of data obtained from analytical, thermoanalytical and mass spectral studies. The structure of the complexes has been discussed in the light of scanning electron microscopy, transmission electron microscopy, molar conductance, magnetic moment, electronic, EPR, IR and FT-IR spectroscopic studies. The magnetic moment value for the chlorido complex (1) suggests weak M-M interaction in the structural unit while very weak interaction in nitrato complex (2) and no interaction in the perchlorato complex (3), respectively. Copper centre has tetragonally distorted octahedral stereochemistry in chlorido and perchlorato complexes while in nitrato complex, copper has distorted square-pyramidal stereochemistry. Zinc(II) metal centre in all heterometal complexes has octahedral stereochemistry. The EPR parameters of the complexes indicate that the copper centre has d(x2-y2) orbital as the ground state. The IR spectral evidences are consistent with the enol form of the dihydrazone ligand in all of the complexes. TEM images showed that the nanoparticle in chlorido complex, are like one dimensional dendrimer or spherical or trigonal prismatic in shape while nitrato complex has spherical and hexagonal shape. The perchlorato complexes show no specific shape and size but the presence of metal lattice is observed. The electron transfer reactions of the complexes have been studied by cyclic voltammetry. (C) 2011 Elsevier B.V. All rights reserved.