Oxidation and reduction behaviour of copper(II) complexes with open-chain analogues of tetra-aza macrocycles

Abstract

The oxidation and reduction behaviour in acetonitrile solution of the copper(II) complexes with a series of linear tetra-amines of varying chain length has been investigated by electrochemical techniques. Copper(III) tetra-amine complexes were found to persist in solution only on the time-scale of the cyclic voltammetry experiment, whereas fairly stable Cu^I complexes were obtained in the case of both the shortest- and the longest-chain tetra-amine ligands investigated. E_½ values for both the Cu^III→ Cu^II and the Cu^II→ Cu^I redox changes have been compared with those reported for corresponding complexes with closed-chain tetra-amines (macrocycles) in order to explore the existence of a ‘macrocyclic effect’.