SYNTHESIS, SPECTROSCOPIC AND REDOX BEHAVIOR OF COPPER(II), NICKEL(II)AND COBALT(II) COMPLEXES OF SOME MACROCYCLIC MULTIDENTATES

Copper(II) complexes of neutral tetradentate diamines and a series of copper(II), nickel(II) and cobalt(II) complexes of a new class of diba sic hexadentate Schiff bases, derived from the above diamines and sali cylaldehyde or 2-hydroxy-1-naphthaldehyde, have been prepared and char acterized by elemental analysis, magnetic susceptibility and IR and el ectronic spectral studies. The electrochemical behaviour of copper(II) and cobalt(II) complexes and ESR spectral parameters of all copper(II ) complexes have also been examined. Ligand field strength increases w ith increase in chelate loop size from six to seven. The ESR spectral data reveal that the copper(II) complexes assume monomeric distorted o ctahedral or pseudo tetrahedral structures. The cyclic voltammetric re dox potentials of copper(II) and cobalt(II) complexes suggest the exis tence of reversible Cu-II/Cu-I and Co-II/Co-I pairs in acetonitrile.