PREPARATION AND PROPERTIES OF HETEROPOLY MOLYBDOVANADATE(V) COMPLEXES

Tetrabutylammonium salts of the mixed heteropoly molybdovanadate(V) anions, [H(x-1)V(V(x)Mo12-x)O-40]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.