Formation et isomerisation des undeca et dodeca tungstosilicates et germanates isomeres

Four undecatungstosilicic and germanic isomers have been prepared. Their UV spectra and their polarograms are given and their acido basic properties are studied. The conditions of formation and the preparations of these isomers are deduced from the reactions of isomerization. A new method for the preparation of β-dodecatungstosilicate is given which do not require fractional crystallisations. This method is valuable for the germanate.