Reactions of Binary Nitrides in Liquid Hydrogen Fluoride and the First Calcium Oxidofluoridometallate of a Group Six Element Ca[Mo2O2F9]2 ⋅ HF

The reactions of the nitrides Mg₃N₂, Ca₃N₂, BN, Si₃N₄ and Mo₂N with anhydrous liquid HF (aHF) were investigated at 20 and 80 °C. While BN, Si₃N₄, and Mo₂N did not react under these conditions, Mg₃N₂ and Ca₃N₂ were converted to MgF₂ and CaF₂. In the reaction of Ca₃N₂ with MoF₆ in aHF, adventitious moisture that diffused through the walls of the reaction vessel led to the formation of the compound Ca[Mo₂O₂F₉]₂ ⋅ HF. We then discovered that it can also be made directly from the reaction of CaCl₂ with MoOF₄ in aHF. The compound was characterized by single crystal and powder X-ray diffraction and quantum-chemical calculations on the solid allowed for the assignment of the IR and Raman bands.