Investigations of (PO4)/(WO6)3-Lattice Components of Keggin's Anion Interaction with Cations in Alkaline-earth Salts of 12-Tungstophosphoric Acid

On the basis of previously recorded Raman and IR spectral data on different crystallohydrates of alkaline-earth 12-tungstophosphoric acid salts (obtained from mother solution and those kept under constant relative humidity (RH) of 35%), an effort was made to determine the position of cations in the Keggin unit. Shifts or band splitting in vibrational spectra of the salts, as well as the changes in band intensities were found to be connected to the cation properties. The spectral data also demonstrated a great influence of cation properties on the secondary structure of Keggin anions and dynamics of protonic species.