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

Area of Science:

• Crystal Engineering
• Supramolecular Chemistry
• Materials Science

Background:

• Understanding the self-assembly of organic salts is crucial for designing new materials.
• Halogen bonding and π-π interactions are key non-covalent forces in crystal engineering.
• Imidazolium salts are versatile building blocks in various chemical applications.

Purpose of the Study:

• To elucidate the crystal structure of a 1,3-bis-(4-bromo-phenyl)imidazolium tetrafluoroborate salt.
• To investigate the role of halogen bonding and other non-covalent interactions in the supramolecular assembly.
• To characterize the formation of 2D sheets and 3D networks within the crystal.

Main Methods:

• Single-crystal X-ray diffraction analysis was employed to determine the crystal structure.
• Analysis of intermolecular interactions, including halogen bonding (F⋯Br, F⋯π), π-π stacking, and C-H⋯F hydrogen bonds.
• Topological analysis using graph sets to describe the hydrogen-bonded ring motifs.

Main Results:

• The crystal structure reveals a 1:1 arrangement of 1,3-bis-(4-bromo-phenyl)imidazolium cations and tetrafluoroborate anions.
• The imidazolium cation exhibits a syn-periplanar conformation with phenyl rings inclined at 36.04°.
• Structure-directing halogen bonds (F⋯Br, F⋯π) and π-π interactions facilitate the formation of 2D supramolecular sheets.
• These sheets are interconnected by C-H⋯F hydrogen bonds, creating a 3D supramolecular network with R2(7) and R2(1)(4) ring motifs.

Conclusions:

• The study successfully characterized the supramolecular architecture of the title salt.
• Halogen bonding and π-π interactions are primary drivers for the formation of 2D sheets.
• Hydrogen bonding further extends the network into a three-dimensional structure, highlighting the interplay of non-covalent forces in crystal engineering.