Isomorphism in Two (E)-1-(4-Halophenyl)-N-[1-(4-Methylphenyl)-1H-Imidazol-4-yl]Methanimines (Halide = Cl, Br)

Abstract

The crystal structures of two imidazole-4-imines, (E)-1-(4-chlorophenyl)-N-[1-(4-methylphenyl)-1H-imidazol-4-yl]methanimine (1, C17H14ClN3), and (E)-1-(4-bromophenyl)-N-[1-(4-methylphenyl)-1H-imidazol-4-yl]methanimine, (2, C17H14BrN3), are isomorphous, the isostructurality index is 99.4 %. Both compounds crystallize in the triclinic space group P-1 with unit cell parameters at 100(1) K as follows: for (1), a = 7.9767(5) A, b = 10.9517(7) A, c = 16.6753(12) A, α = 80.522(6)°, β = 87.046(6)°, γ = 89.207(5)°, and for (2), a = 8.0720(7) A, b = 10.9334(10) A, c = 16.8433(13) A, α = 81.161(7)°, β = 86.605(7)°, γ = 89.505(7)°. The structures contain two symmetry—independent but conformationally similar molecules in the asymmetric unit (Z’ = 2). In both compounds the overall twist of the molecule, defined as the dihedral angle between the terminal phenyl ring planes is significant, around 56°. The crystal packing is determined mainly be weak specific intermolecular interactions: the C–H···N hydrogen bonds connect molecules into infinite chains, and the chains are linked via C–H···X hydrogen bonds and by π–π interactions. This study illustrates the significant role of the weak interactions, which—in spite of their weakness—can robustly repeat in the crystal structures of similar compounds. Two imidazole-4-imines, (E)-1-(4-chlorophenyl)-N-[1-(4-methylphenyl)-1H-imidazol-4-yl]methanimine, and (E)-1-(4-bromophenyl)-N-[1-(4-methylphenyl)-1H-imidazol-4-yl]methanimine, are isomorphous, the isostructurality index is 99.4 %.