SYNTHESIS AND CHARACTERIZATION OF VANADIUM-SUBSTITUTED HETEROPOLY MOLYBDOSULFATE(VI) COMPLEXES

Monovanadium derivatives of 12-molybdosulfate(VI) and 18-molybdodisulfate(VI), [S(VMo11)O40]3- and [S2(VMo17)O62]5-, have been prepared as tetrabutylammonium (n-Bu4N+) salts from a Mo(VI)-V(V)-H2SO4-CH3CN system. Both mixed molybdosulfate(VI) comlexes were characterized by their IR and UV spectra and their voltammetric behaviors. These mixed complexes are stable in nonaqueous solutions. In a 90% (v/v) CH3CN-0.1 M (M = mol dm-3) HClO4 system, the [S(VMo11)O40]3- anion transforms spontaneously into 12-molybdovanadate(V), whereas the [S2(VMo17)O62]5- anion is stable. In a 90% (v/v) CH3CN-0.5 M HClO4 system, on the other hand, both mixed complexes change into 18-molybdodisulfate(VI), [S2Mo18O62]4-.