Tungsto-arsenates arsenic acids

Tungsto-arsenic Acids and Tungsto-arsenates.—These compounds are analogous to the phosphotungstic acids and their salts (see this Series, Vol. VII, Part III), but the complex anions are... 

The use of heteropoly anions as catalysts, however, was not new for the Eni researchers involved in oxidation chemistry. Some very peculiar heteropolyanions had been discovered at the Istituto Donegani at the beginning of the 1980s. Basically, they were quaternary ammonium (or phosphonium) salts of a new class of peroxidic tungsto-phosphates or arsenates in which the W (or Mo) to P (or As) ratio was as low as four the best known, a typical example of this class, is the PW4O2J anion, which was also the first peroxidic derivative of a heteropolyacid whose structure was solved. Both the free acid and the reduced forms of these heteropolyanions are unstable, and it was not possible to isolate them. 

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