Synthesis, spectroscopic and electrochemical studies of copper(II) and cobalt(II) complexes of three unsymmetrical vic -dioximes ligands

Abstract

Cobalt(II) and copper(II) complexes with three dioxime ligands cyclohexylamine-p-tolylglyoxime (L1H2), tert-butyl amine-p-tolylglioxime (L2H2) and sec-butylamine-p-tolylglyoxime (L3H2), have been prepared. The metal to ligand ratios of the complexes were found to be 1 : 2. The Cu(II) complexes of these ligands are proposed to be square planar; the Co(II) complexes are proposed to be octahedral with water molecules as axial ligands. Ligands and complexes are soluble in common solvents such as DMSO, DMF, CHCl3 and C2H5OH. The ligands have been characterized by elemental analysis, IR, UV-VIS, 1H NMR, 13C NMR and thermogravimetric analysis (TGA). The complexes were characterized by elemental analysis, IR, UV-VIS, magnetic susceptibility measurements, thermogravimetric analysis (TGA) and electrochemistry. Electrochemical properties of metal complexes show quasi-reversible one-electron redox processes. However, Co(L1H)2 and Cu(L1H)2 complexes show another oxidation peak in the positive region. This single irreversible oxidation peak is caused by the cyclic ring of the ligand. Data also revealed that the electron transfer rates of metal complexes with L1H2 are higher than the other complexes.