An X-ray study of the cæsium salts of certain 12-heteropoly acids

Abstract

Abstract Phosphotungstic acid has two hydrates-both cubic-whose structures were recently determined by Keggin. If the acid is crystallized out of solution it forms a 29-hydrate which loses water when exposed to the air. A 5-hydrate is formed when the 29-hydrate is dehydrated over P2O5 until constant weight is reached. Keggin's structure for the 5-hydrate led to the formula H3PW12O40. 5H2O. Other workers proved that silico-, boro-, and metatungstic acids, when dehydrated over P2O5, also formed 5-hydrates with similar structures, their formulae being H4SiW12O40. 5H2O, H5BW12O40. 5H2O, and H6H2W12O40. 5H2O. The object of the present research was to examine the structures of salts of these acids. A beginning was made with caesium salts mainly because it was anticipated that the heavy caesium atoms would be more readily located.