SYNTHESIS, CHARACTERIZATION AND ELECTROCHEMICAL-BEHAVIOR OF SOME COPPER(II) COMPLEXES WITH LINEAR AND TRIPODAL TETRADENTATE LIGANDS DERIVEDFROM SCHIFF-BASES

New copper(II) complexes [Cu(H2L)(H2O)(n)]Cl-2 . xH(2)O (n = O or 2) w ith 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 stud ies support the binding of linear ligands with two N and two O donor s ites to copper(II) ion, providing a square planar geometry and show al so that tripodal ligands were coordinated to the metal ion by only one nitrogen atom, giving an arrangement of NO3 donor groups, the other a xial sites being occupied by the solvent. The ESR data indicate that t he covalent character of the metal-ligand bonding in the copper(II) co mplexes increases with increasing electron donating effect of the liga nd 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 infl uencing the redox potentials of the complexes. (C) 1997 Elsevier Scien ce Ltd.