Electrochemical studies of copper(II) complexes with Schiff-base ligands

Abstract The electrochemical reduction of copper(II) complexes with salen Schiff-base ligands derived from ethylenediamine or ( R , R ) or ( S , S )-1,2-diphenylethylenediamine and 5-methoxy, 5-bromo and 5-nitrosalicylaldehyde have been studied by cyclic voltammetry in the potential range +1 to −2.3 V in dimethyl sulfoxide (DMSO) as a solvent. The resulting voltammograms consist of a single quasi-reversible one-electron transfer attributable to the couple [Cu(II)L]/[Cu(I)L] − . Trends in cathodic peak potential ( E pc ) values are observed which can be correlated with the electronic effects of the 5-substituents of the Schiff-base ligands. Changes in the basicity of the ligand groups are determinant for such electrochemical trends.