Oxidation and reduction behavior of copper(II) complexes with open-chain analogs of tetraaza macrocycles

Electrochem. methods were used to study the redox behavior of the Cu(II) complexes of H2N(CH2)nNH(CH2)mNH(CH2)nNH2 (n, m = 2, 3) in MeCN. Cu(III) complexes persisted in soln. only on the time-scale of the cyclic voltammetry expt., whereas fairly stable Cu(I) complexes were obtained with both the shortest- and longest-chain ligands studied. Electrode potentials for both the Cu(III) → Cu(II) and Cu(II) → Cu(I) redox reactions were compared with those reported for the corresponding complexes with macrocyclic tetraamines.