Spectroscopic, thermal and electrochemical characterization of synthesized divalent transition metal complexes with cysteine and 4-substituted thiosemicarbazides

Abstract

Mixed ligand complexes of CoII, NiII and CuII with cysteine and 4-substituted thiosemicarbazides (l1–l3) have been synthesized. The elemental analyses, molar conductance, spectra [electronic, i.r., 1H-n.m.r., mass] and thermal studies were used to characterize the isolated complexes. Cyclic voltammetry was used to study the electrochemical behaviour of the NiII complexes. The i.r. and 1H-n.m.r. showed that cysteine is deprotonated in the complex and acts as a binegative ligand coordinating through thiol sulphur and COOH groups. Also, thiosemicarbazides act as a bidentate ligand, coordination via NH2 and (C=S) groups. Square-planar geometry has been proposed for CoII, NiII and CuII ternary complexes.