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, C(11)H(8)N(4)O(2), and 1-(4-chlorophenyl)-2-methyl-4-nitro-1H-imidazole-5-carbonitrile, C(11)H(7)ClN(4)O(2), 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 C[triple-bond]N.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.