Relations entre les tungstophosphates apparentés à l'anion PW12O403−. Synthèse et propriétés d'un nouveau polyoxotungstophosphate lacunaire K10P2W20O70•24H2O

The relationship between all the polyoxotungstophosphates related to PW12O403− and P2W21O716− anions was established. A new compound K10P2W20O70 was synthesized and characterized by infrared and Raman spectroscopy. These properties, and especially the 31P and 183W nuclear magnetic resonance spectra, allowed us to propose the structure. It is a lacunary species that reacts with Co(II) to give two 1–1 complexes, probably coordination isomers. In the presence of Co(II) the A-type → B-type PW9 isomerization occurs in several steps, which are specified. The tungstophosphate β isomers are less stable than the corresponding tungstosilicates or germanates, and β-PW12 was only identified as a reduced species PW12O404−.