Spectroscopic and voltammetric studies on the formation of Keggin-type V(V)-substituted tungstoarsenate(V) and -phosphate(V) complexes in aqueous and aqueous-organic solutions

Abstract

The tetra-n-butylammonium salts of [AsV x W 12− x O 40] (3+ x)− ( x=1–2) were isolated from an acidic aqueous-CH 3CN solution and characterized by elemental analysis, FT-IR, UV–Vis and cyclic voltammetry. The formation conditions of Keggin-type V(V)-substituted tungstoarsenate(V) and -phosphate (V) complexes were elucidated by cyclic voltammetry, Raman spectroscopy, and 31P NMR in aqueous and aqueous-organic solutions. It was found that water-miscible organic solvents such as acetonitrile and acetone, affected the conversion processes of [XW 12O 40] 3− into [XV x W 12− x O 40] (3+ x)− (X=P or As). It was suggested that these results were due to the stabilities of [XW 12O 40] 3− in aqueous and aqueous-organic solution.