COMPARISON OF ELECTROCHEMICAL-BEHAVIOR OF CU(II), CO(II), NI(II), ANDFE(III) SCHIFF-BASE TYPE COMPLEXES

The electrochemical oxidation of Cu(II), Co(II), and Ni(II) complexes and reduction of Fe(III) complexes with a series of substituted N,N'-e thylenebis(monooxo-R-acetoimines) H(2)N(2)O(2)R(2), where R = 4-OCH3C6 H4, 4.CH3C6H4, C6H5, CH3, 4-FC6H4, 4-ClC6H4, 4-BrC6H4, and 4-NO2C6H4, were investigated by cyclic voltammetry in acetonitrile and methanol s olutions at a platinum electrode. The anodic peak potentials for the c opper and nickel complexes varied linearly with the Taft resonance sub stituent constant, whereas for the cobalt and iron complexes such a re lationship between the formal potentials and the Taft resonance substi tuent constant was not observed. The symmetry of redox orbitals is con sidered.