Preparation and Properties of Heteropoly Molybdovanadate(V) Complexes

Abstract

Tetrabutylammonium salts of the mixed heteropoly molybdovanadate(V) anions, [H_x−1V(V_xMo_12−x)O₄₀]⁴⁻ (x=1–3) were prepared from a Mo(VI)–V(V)–CH₃CN system at room temperature. These mixed heteropoly anions were distinguished by their voltammetric behavior; the anions with x=1, 2, and 3 were electroreduced by one-, two-, and three-electrons due to the peripheral V atoms at a glassy carbon electrode. The spectroscopic properties were also reported. Their formation conditions were compared with those of 12-molybdovanadate (V), [VMo₁₂O₄₀]³⁻, especially regarding the concentrations of Mo(VI), V(V), acid, and organic solvents, the nature of organic solvents, and the ionic strength of the system. It should be emphasized that the 12-molybdovanadate(V) and mixed molybdovanadate(V) complexes are not formed in the absence of organic solvents.