Hydrolysis of ammonium oxofluorotungstates: A 19F, 17O and 183W NMR study

Fluorine-19 and natural abundance 17O and 183W NMR spectroscopy were employed for the characterization of aqueous solutions of (NH4)2WO2F4 and (NH4)3WO3F3. Dissolution of the (NH4)2WO2F4 complex is accompanied by its partial acid hydrolysis to give the trans(mer)-dimer, [W2O5F6]4−, and unreacted cis-[WO2F4]2−. The cis(fac)-[W2O5F6]4− anion is the major soluble product resulting from the alkaline hydrolysis of (NH4)2WO2F4 along with the isolation of the solid (NH4)2WO3F2. In addition, the edge-bridging dimer, [W2O6F4]4−, and the cyclic trimer, [W3O9F6]6−, are also suggested as hydrolysis products. Decomposition of (NH4)3WO3F3 occurs in aqueous solution to give NH4WO3F.