Crystal structure, DFT calculation, Hirshfeld surface analysis and energy framework study of 6-bromo-2-(4-bromophenyl)imidazo[1,2-a]pyridine

Abstract

The title imidazo[1,2-a] pyridine derivative, C13H8Br2N2, was synthesized via a single-step reaction method. The title molecule is planar, showing a dihedral angle of 0.62 (17)° between the phenyl and the imidazo[1,2-a] pyridine rings. An intramolecular C—H...N hydrogen bond with an S(5) ring motif is present. In the crystal, a short H...H contact links adjacent molecules into inversion-related dimers. The dimers are linked in turn by weak C—H...π and slipped π–π stacking interactions, forming layers parallel to (110). The layers are connected into a three-dimensional network by short Br...H contacts. Two-dimensional fingerprint plots and three-dimensional Hirshfeld surface analysis of the intermolecular contacts reveal that the most important contributions for the crystal packing are from H...Br/Br...H (26.1%), H...H (21.7%), H...C/C...H (21.3%) and C...C (6.5%) interactions. Energy framework calculations suggest that the contacts formed between molecules are largely dispersive in nature. Analysis of HOMO–LUMO energies from a DFT calculation reveals the pure π character of the aromatic rings with the highest electron density on the phenyl ring, and σ character of the electron density on the Br atoms. The HOMO–LUMO gap was found to be 4.343 eV.

Keywords

• crystal structure
• imidazole-pyridine derivative
• π–π interactions
• dft calculation
• hirshfeld surface analysis
• energy framework
• frontier molecular orbitals