Fluoridobromate(V)-hydrogen fluoride cocrystals.

Area of Science:

• Inorganic Chemistry
• Crystallography
• Solid-State Chemistry

Background:

• Bromine pentafluoride (BrF5) is a reactive interhalogen compound.
• Fluoride salts and hydrogen fluoride are known to form complex structures.
• Previous studies on [Br3F16]- anion revealed propeller-like coordination motifs.

Purpose of the Study:

• To synthesize and characterize novel cocrystals of BrF5 with HF2- and H2F3- anions.
• To elucidate the crystal structures and coordination chemistry of these new compounds.
• To investigate the structural motifs and bonding in the BrF5-HF systems.

Main Methods:

• Single-crystal X-ray diffraction for structure determination.
• Quantum chemical calculations for solid-state properties.
• Raman spectroscopy for vibrational analysis.

Main Results:

• First-time synthesis of cocrystals [NMe4][(BrF5)6(HF2)] and Cs2[(BrF5)6(HF2)(H2F3)].
• Crystal structures reveal discrete [HF2]- and [H2F3]- anions coordinated by BrF5 molecules.
• A recurring propeller-like coordination motif of BrF5 around fluoride atoms was observed.

Conclusions:

• Novel cocrystal structures involving BrF5 and hydrogen fluoride anions have been successfully synthesized and characterized.
• The coordination chemistry highlights the ability of BrF5 to act as a Lewis acid coordinating to fluoride anions.
• The identified structural motifs provide insights into the reactivity and complex formation of interhalogen compounds.