Cyano-cyano and chloro-cyano interactions in two imidazole derivatives

In two closely related 1-aryl-2-methyl-4-nitro-5-cyanoimidazoles, namely 2-methyl-4-nitro-1-phenyl-1H-imidazole-5-carbonitrile, C11H8N4O2, and 1-(4-chlorophenyl)-2-methyl-4-nitro-1H-imidazole-5-carbonitrile, C11H7ClN4O2, different weak intermolecular interactions determine the crystal packing. In the 1-phenyl derivative, dipole-dipole interactions between antiparallel cyano groups connect molecules into centrosymmetric dimers, while in the 1-(4-chlorophenyl) derivative, the dimers are connected by Cequivalent toN...Cl-C halogen bonds. These interactions, together with weak C-H...O(N) hydrogen bonds, connect molecules related by subsequent centres of inversion into infinite tapes.