Fluoridobromate(V)–Hydrogen Fluoride Cocrystallizates

Abstract

Cocrystallizates of fluoridobromate(V) anions and hydrogen fluoride have been obtained for the first time in the form of the two compounds [NMe₄][(BrF₅)₆(HF₂)] and Cs₂[(BrF₅)₆(HF₂)(H₂F₃)]. These compounds are formed when hydrogen fluoride is present in reactions of BrF₅ and a fluoride ion source, such as [NMe₄]F or CsF. Here we present the crystal structures of the compounds, complemented by quantum chemical solid-state calculations, and our Raman spectroscopic investigations on the compound [NMe₄][(BrF₅)₆(HF₂)]. The cocrystallizates contain discrete [HF₂]^– and [H₂F₃]^– anions, which are coordinated by BrF₅ molecules via their F atoms. The propeller-like coordination of an F atom by three BrF₅ molecules, as known from the [Br₃F₁₆]^– anion, appears as a recurring structural motif in these compounds.