SOLID-STATE REACTIONS OF CHROMIUM(III)-SUBSTITUTED HETEROPOLY TUNGSTATES WITH CHROMIUM(III) AMMINE CATIONS

The reaction of chromium ammine complexes with chromium-substituted Ke ggin anions in aqueous solution forms insoluble salts which were then heated to temperatures of 240 and 350 degrees C. The thermal behaviour of the ammine complexes is dominated by a strong exothermic reaction which is interpreted as a linking reaction (condensation) between chro mium from the complex ammine cation and the heteropolyanion. Thermal t reatment of the title compounds yields products that are soluble in wa ter and could be crystallized as potassium salts in several cases. A c hromium-caped Keggin anion is the proposed structure.