17O NMR spectra and isotope exchange of oxygen in aqueous solutions of phosphorus-vanadium-tungsten heteropoly acids

1. The authors have measured the chemical shifts of the17 O NMR and the rate of exchange of the isotope17 O between the polyanions and water in aqueous solutions of mixed P-V-W heteropoly acids containing 1–4 vanadium atoms. 2. The O atoms of different types in the structure of the heteropoly anions are exchanged at different rates; the rate of exchange depends on the composition of the anion. 3. The rate of isotope exchange of oxygen in aqueous solutions of P-V-W heteropoly acids is lower than in solutions of the analogous P-V-Mo heteropoly acids.