Constitution of the Poly-acids

Abstract

THE work of Keggin¹ has placed the constitution of the 12-heteropoly-acids, metatungstates and metamolybdates—for example, R₃H[SiW₁₂O₄₀].aq, R₆[H₂Mo₁₂O₄₀].aq.—on a sure basis, and has indicated that the poly-acid anions may be regarded as coordination structures, built up of polyhedra of oxygen ions in the manner first envisaged by Pauling². The constitution of other groups of poly-acids, for example, those with 9 or 11 MoO₃ or WO₃ for each molecule of hetero-acid, is still quite unknown, as also is that of the second main series of poly-acids—the 6-poly-acids, such as the 6-molybdo-periodates.