An electrochemical study of the trinuclear Cu (II), Co (II), Co (III) and pentanuclear Cu (II) complexes of the vic-dioxime substituted with 14-membered N₂O₂ macrocycles

Trinuclear Cu(II), Co(II), Co(III) and pentanuclear Cu(II) complexes of a vic-dioxime substituted with 14-membered N₂O₂ macrocycles (LH₄) have been studied in dimenthyl sulphoxide solution by cyclic voltanimetric methods. The cyclic voltammogram of Cu(II) complex of LH₄ is characterized by two one-electron reduction waves. For the pentanuclear Cu(II) complex four one- electron reduction waves are observed. These waves are all quasi- reversible at all sweep rates studied. The cyclic voltammograms of trinuclear Co(II) and Co(III) complexes show two one-electron reduction waves which have also quasi reversible character. The heterogeneous electron transfer rates are slow for all these complexes, so that peak separations between the cathodic and anodic waves vary with the sweep rates. The reaction mechanisms and diffusion coefficients have been investigated in this work.