CYCLIC VOLTAMMETRY AND SPECTROELECTROCHEMISTRY OF OSMIUM PHTHALOCYANINES IN AQUEOUS AND NONAQUEOUS SOLVENTS

Cyclic voltammetry of osmium phthalocyanine complexes, [(CN)(2)Os(II)P c](2-) and (py)(2)Os(II)Pc (Pc = phthalocyanine dianion), show two oxi dation couples and two reduction couples in acetonitrile and dimethylf ormamide. Oxidation and reduction in these complexes occur at the ring to form cation and anion radical species, respectively. The [(CN)(2)O s(II)Pc](2-) complexes show a remarkable ease of ring oxidation with o xidation potentials that are much lower than is typical for metallopht halocyanines. Half-wave potentials of 0.25 and 0.67 V (versus saturate d calomel electrode, SCE) were obtained for the first and second ring oxidations, respectively. The [(CN)(2)Os(II)Pc](2-) complex is soluble in water at pi-Is greater than 4. This complex shows one oxidation co uple in pH 9 buffer at -0.11 V versus SCE. Copyright (C) 1996 Elsevier Science Ltd