AQUEOUS VANADOSILICATES

Silicate anions were shown by V-51 and O-17 NMR spectroscopy to combin e with aqueous [HVO4](2-) in aqueous alkaline solution, forming the an ions [H2VSiO7](3-), [H3VSiO7](2-) and various related monovanadooligos ilicate species. Approximate equilibrium constants have been derived; and shown to depend only weakly upon ionic strength. The ion [H2VSiO7] (3-) at higher concentrations also dimerises to give an anion with a S iOVOVOSi linkage, as shown by selective inversion-transfer subtraction spectra.