State of Silicotungstic Acid in Aqueous Solutions in the Presence of Inorganic Salts as Probed by NMR Spectroscopy

The state of silicotungstic acid (STA) in the presence of inorganic salts (Fe 2 (SO 4 ) 3 , SnCl 2 , and SnSO 4 ) in aqueous solutions was studied by 183 W NMR spectroscopy. Silicotungstic acid was found to retain its structure, and no new heteropoly compounds were formed. This finding proves the enhanced stability of STA toward complex formation at high acidities.