Une nouvelle forme de trioxyde de tungstene: Les oxydes WO3 et WO3·O,5H2O a structure pyrochlore

A new form of tungstene trioxide characterized by a cubic pyrochlore structure has been isolated by soft chemistry, using the thermolysis of the tetragonal hydronium tungstate: (H3O)20+x(W4O6)1/3−x/12W32O108. The anhydrous WO3 absorbs atmospheric water leading to the oxide WO3·O, 5H2O without destruction of the structure. The structural study of the hydrated cubic pyrochlore WO3·O, 5H2O shows that the host lattice W2O6 is stoichiometric and that the water molecules are located in the “O16” cages. The topotactic nature of the dehydration reaction is discussed.