Structure of Silico‐Tungstic Acid in Aqueous Solution

The structure of 12‐silico‐tungstic acid, H4SiW12O40, in aqueous solution has been investigated by x‐ray diffraction. The results indicate that 12 tungsten atoms are contained in a monodisperse species with arrangement similar to that found in the crystalline acid. Each tungsten atom has two near tungsten neighbors at each of the distances 3.36 A and 3.71 A.