Formation of voltammetrically-active isopolyoxotungstate complexes in aqueous CH3CN media

A new route to the preparation of voltammetrically-active isopolyoxotungstate complexes was developed by the presence of CH3CN in aqueous W(VI) solutions. In the presence of 40% (v/v) CH3CN as an auxiliary solvent, the [W6O19]2− complex was formed in equilibrium with the [W10O32]4− complex, which was subsequently transformed into the previously unknown α-Keggin-type [H4W12O40]4− complex at weaker acidities. The α-[H4W12O40]4− complex was characterized by voltammetric and spectroscopic behaviors.