AQUEOUS TUNGSTOVANADATE EQUILIBRIA

A combined equilibrium study of tungstovanadates involving potentiomet ry and V-51, W-183 and O-17 NMR spectroscopy has been able to identify 11 main species, giving their formation Constants and pK(a) values wh ere relevant. Tentative identification was also made of two other non- equilibrium species at lower pH values, in addition to those with a V- centred Keggin structure. The V-51 shifts of the unprotonated hexameta late anions fall into a rational pattern, and the formation constants are all higher than those of the corresponding molybdovanadate species , where comparisons are possible.