Voltammetric studies of polyoxometalate microparticles in contact with the reactive distillable ionic liquid DIMCARB

Abstract

The voltammetry of the polyoxometalate salts [Bu 4N] 4[SiW 12O 40] (α, β, γ* isomers), [Bu 4N] 4[S 2W 18O 62] (α, γ* isomers) and [Bu 4N] 4[S 2Mo 18O 62] (α isomer) has been studied in the “distillable ionic liquid” DIMCARB (a mixture of adducts, both ionic and neutral, of dimethylamine and carbon dioxide). Dissolution of these salts tended to be slow and the anions, except [α-SiW 12O 40] 4−, reacted with DIMCARB. However, high quality voltammograms were obtained from microparticles of the salts adhered to a glassy carbon electrode in contact with DIMCARB. Rapid dissolution of the reduced forms of each of the polyoxometalate anions provided reversible potential data. The higher basicity of the more highly reduced anions promoted interactions with the acidic solvent component of this medium. Comparison of reversible potentials indicated that the polarity of DIMCARB is similar to CH 3CN, but smaller than that of conventional non-volatile ionic liquids and water.