Cy. Rong et Fc. Anson, SIMPLIFIED PREPARATIONS AND ELECTROCHEMICAL-BEHAVIOR OF 2 CHROMIUM-SUBSTITUTED HETEROPOLYTUNGSTATE ANIONS, Inorganic chemistry, 33(6), 1994, pp. 1064-1070
Simplified preparative procedures are described for the generation of
alpha-[PW11O39Cr(III)(OH2)]4- and alpha2-[P2W17O61-Cr(III)(OH2)]7-anio
ns which can be readily oxidized, chemically or electrochemically, to
alpha-[PW11O39Cr(V)O]4- and alpha2-[P2W17O61Cr(V)O]7-. The oxidized co
mplexes are stable in aqueous solutions. They react with benzyl or eth
yl alcohol, but the rates of the oxidations are too slow to make the C
r(V) derivatives attractive as electrocatalysts. The voltammetry of th
e Cr(V)/Cr(III) couples is only quasi-reversible, but approximate form
al potentials with their pH dependencies are reported. Diffusion coeff
icients evaluated for the polyanions show the larger anion to diffuse
more slowly and neither anion to be highly hydrated.