1,3-Bis(4-bromo-phen-yl)-1H-imidazol-3-ium tetra-fluoro-borate

The crystal of the title salt, C₁₅H₁₁Br₂N₂ ⁺·BF₄ ^-, contains one half of a 1,3-bis-(4-bromo-phen-yl)imidazolium cation and one half of a tetra-fluoro-borate anion in the asymmetric unit; the complete ions are generated by crystallographic twofold symmetry. The imidazolium cation adopts a syn-periplanar conformation, with the 4-bromo-phenyl rings inclined to the central imidazolium ring by 36.04 (4)°. In the crystal, the tetra-fluoro-borate anion participates in structure-directing halogen-bonding contacts through F⋯Br and F⋯π(phen-yl) inter-actions. These are complemented by inter-molecular π-π and Br⋯π inter-actions, which assemble the ions into two-dimensional supra-molecular sheets lying parallel to the ac plane. The sheets are further linked by C-H⋯F hydrogen bonds, forming ring motifs of graph sets R ² ₂(7) and R ² ₁(4) within a three-dimensional supra-molecular network.