Crystal packing modes of 1-(4′-aryl)-4-nitro-5-methylimidazoles: π-stacking, weak hydrogen bonds and C–Cl⋯O halogen bonds

Abstract

The crystal structures of four derivatives of 1-phenyl-4-nitro-5-methylimidazole have been determined by means of X-ray crystallography at 100(1) K. The interplay of different weak intermolecular interactions: π-stacking, C–H⋯O, C–H⋯N hydrogen bonds and C–Cl⋯O halogen bonds determine the supramolecular architecture of these compounds. The crystal packing modes of 1-phenyl and 1-(4′-methylphenyl) derivatives are almost identical: there are stacks of molecules additionally strengthened by C–H⋯N and C–H⋯O hydrogen bonds, and these stacks are connected into chains by relatively strong, bifurcated C–H⋯O hydrogen bonds. In 1-(4′-chlorophenyl) derivative the strong and linear C–Cl⋯O halogen bonds together with the C–H⋯O hydrogen bonds connect the stacks into two-dimensional grids. In these three structures there are homogenous stacks: imidazole rings are almost parallel. The heterogeneous stacks (–phenyl/imidazole/phenyl–) are observed in 1-(4′-methoxyphenyl)-4-nitro-5-methylimidazole. In this case there are no hydrogen bonds within the stack, there are only interstack interactions.