X-ray crystal structural and spectral studies of copper(II) and nickel(II) complexes of two asymmetric bis(thiosemicarbazone) ligands and the investigation of relationship between the N(4)-substituent and the electrochemical behavior

Abstract

Asymmetric, potentially tetradentate ligands (H2L5, H2L6·2MeOH) are formed by subsequent condensation a 4-chlorophenyl thiosemicarbazide and 4-phenyl thiosemicarbazide for H2L5, 4-chlorophenyl thiosemicarbazide and 4-bromophenyl thiosemicarbazide for H2L6·2MeOH on dialdehyde (1). The mixed bis(thiosemicarbazones) and their copper(II) and nickel(II) complexes have been characterized with1HNMR, IR, electronic spectra and X-ray crystallography. Both bis(thiosemicarbazones) form square-planar N2S2complexes with nickel(II) and copper(II). Electrochemical investigation showed that all Cu(II) and Ni(II) complexes were reducible. The differences observed in the electrochemistry between symmetric and..