Voltammetric and spectroscopic behaviour of the copper adducts of thiol and thioether ligands under aerobic and anaerobic conditions

Joint spectroscopic (ESR, electronic absorption and FT IR) and voltammetric (square-wave and cyclic voltammetry) techniques were employed to investigate the properties of copper adducts with cysteine, N-acetylcysteine and methionine under aerobic and anaerobic conditions. The metal oxidation state in the solid and solvated adducts adheres to the presence of oxygen, whereas ESR results (g_∥ = 2.245, g_⊥ = 2.059, A_∥ = 170 Gauss) reveal tetragonally distorted octahedral copper(II) environment under aerobic circumstances. In presence of the thiol and thioether ligands under nitrogen voltammetric measurements evidence formation of copper(I) species.