Synthesis, characterization and electrochemical behaviour of some copper(II) complexes with linear and tripodal tetradentate ligands derived from Schiff bases

Abstract

New copper(II) complexes [Cu(H 2L)(H 2O) n ]Cl 2· xH 2O ( n = 0 or 2) with linear and tripodal tetradentate ligands have been synthesized and characterized using elemental analysis, molar conductance, IR spectra, magnetic measurements, electronic and ESR spectra. The spectral studies support the binding of linear ligands with two N and two O donor sites to copper(II) ion, providing a square planar geometry and show also that tripodal ligands were coordinated to the metal ion by oly one nitrogen atom, giving an arrangement of NO 3 donor groups, the other axial sites being occupied by the solvent. The ESR data indicate that the covalent character of the metal-ligand bonding in the copper(II) complexes increases with increasing electron donating effect of the ligand substituents R. From the results of cyclic voltammetry, it is shown that chelate structure and ligand geometry, steric bulk and electron donating effects of the ligand substituents are among the factors influencing the redox potentials of the complexes.