Synthesis and Characterization of A[W2O2F9] (A = Li - Cs)

Herein, we report upon the in situ formation of WOF4 and its subsequent reaction with AF (A = Li - Cs) in aHF to produce A[W2O2F9] (A = Li - Cs). Structural analysis of the obtained compounds was performed using single-crystal X-ray diffraction. A comparison of the single-crystal structures obtained here to the previously reported A[Mo2O2F9] (A = Li - Cs) and H3O[W2O2F9] salts is given. Additionally, IR and Raman spectroscopy were used to characterize each salt. These spectra were compared to calculated ones for the solid-state structure of each salt using the DFT-PBE0 density functional method. The calculated spectra were used to assign bands in the experimental spectra. Both MoOF4 and WOF4 gave similar reaction products under similar reaction conditions. It was concluded that the oxyfluorides show similar Lewis acid-base reactions with the alkali metal fluorides in aHF solutions.