Solvation effect of Li + on the voltammetric properties of [PMo 12O 40] 3− in binary solvent mixtures

Abstract

The conversion process between one- and two-electron waves for [PMo 12O 40] 3− was investigated in a binary mixture of acetonitrile and solvent S (S= N, N-dimethylformamide (DMF), dimethylsulfoxide (DMSO), H 2O, propylene carbonate (PC), or 1,4-dioxane) containing 0.10 M (M=mol dm −3) LiClO 4. A reversible two-electron wave was obtained in a binary mixture of acetonitrile and 1,4-dioxane. On the other hand, the first two-electron wave was converted into two one-electron waves in a mixture of acetonitrile and DMF, DMSO, H 2O, or PC. The 7Li-NMR studies demonstrated preferential solvation of Li + by one of the solvents with stronger Lewis basicity. The electrode process was explained on the basis of the relative permittivity ( ε r) of the mixed solvent and the relative donicity of acetonitrile and solvent S. It turned out that the number of transferred electrons at the electrode could be controlled by a proper choice of binary solvent mixtures.