Synthesis, spectral and electrochemical properties of divalent metal complexes containing thiohydrazone and thiosemicarbazone ligands

The L(1)H(4) and L(2)H(6) complexes of metal halides MX(2) (M = Cu, Ni, Co, Zn, Cd or Hg, X = Cl, Br or I) have been prepared. The complexes were characterized on the bases of H-1 NMR, IR, electronic and mass spectra, magnetic studies, conductance and analytical data. The stoichiometry and the spectroscopic data indicate that the complexes 1-8, 11, 12 and 15 the metal ions are coordinated by ligand anions and the complexes 9, 10, 13, 14 and 16 contain the neutral ligand. Electrochemical behaviour of nickel and cobalt complexes was determined by cyclic voltammetry. The reduction of complexes are related to metal-centred reductions. In addition, complexes 3, 11 and 12 show irreversible waves associated to Ni(II)/Ni(III) process. The reduction/oxidation potentials depend on the unsaturation grade present in the complexes.