One-electron reduction of the gamma*-isomer of [S2W18O62](4-) leads to isolation of the alpha-isomer

Bu4N+ salts of [S2W18O62](5-) and [S2W18O62](6-) can be isolated by electro reduction of gamma*-(Bu4N)(4)[S2W18O62] in MeCN. alpha-(Bu4N)(5)[S2W18O62] . 4MeCN crystallizes in space group C2/c with a = 26.226(2) Angstrom, b = 1 5.570(2) Angstrom, c = 38.407(2) Angstrom, beta = 115.59(2)degrees, V = 14 145(2) Angstrom (3), and Z = 8. The observations indicate that a gamma* - a lpha isomerization is associated with the [S2W18O62](4-)- [S2W18O62](5-) co uple. However, the transformation could not be detected on the timescale of cyclic voltammetry up to a scan rate of 10 V s(-1). The available data sug gest that either: (i) the gamma* - alpha equilibrium favors one of the isom ers in solution for both redox states, or (ii) the isomerization is slow on the cyclic voltammetric timescale but the differences in E-1/2 values for the alpha-[S2W18O62](4-)-[S2W18O62](5-) and gamma*-[S2W18O62](4-)-[S2W18O62 ](5-) couples cannot be resolved by cyclic voltammetry.