31P NMR and Raman spectroscopic and voltammetric studies on the formation and conversion processes of Keggin-type molybdotungstophosphate(V) and -arsenate(V) complexes in aqueous-organic solvents

The formation conditions of Keggin-type molybdotungstophosphate(V) (PWxMo12 − xO40 3− (PWxMo12 − x), x=0–12) and -arsenate(V) (AsWxMo12 − xO40 3− (AsWxMo12 − x)) complexes in aqueous-organic solvents were investigated with 31P NMR, Raman spectroscopy, and cyclic voltammetry. The conversion processes of the PMo12 and the PW12 anions into the PWxMo12 − x anions were also examined and compared with those of the AsMo12 and AsW12 anions into the AsWxMo12 − x anions. The mean vibration frequencies of the PWxMo12 − x and AsWxMo12 − x (x=1–11) complexes were calculated in IR and Raman spectra from those of the PMo12 and PW12, and AsMo12 and AsW12 complexes, respectively.