Synthesis, crystal and molecular structures of 1-n-butyl-2-(3 '-chlorophenyl)-1H-benzimidazole-5-carbonitrile hemihydrate and 1-n-butyl-2-(3 ',4 '-dimethoxyphenyl)-1H-benzimidazole-5-carbonitrile

Abstract

Two types of 5-cyanobenzimidazole derivatives with 1-n-butyl-2-(3'-chlorophenyl), (C18H16N3Cl)(2)center dot H2O (1) and 1-n-butyl-2-(3',4'-dimethoxyphenyl), (C20H21N3O2) (2) were prepared and their crystal structures were solved and reported. (1) crystallizes in the triclinic space group P(1) over bar with a = 8.7682(7), b = 12.9392(10), c = 15.4435(12) angstrom, alpha = 81.401(6)degrees beta = 76.073(6 degrees, gamma = 479(6)degrees, Z = 2, V = 1651.4(2) angstrom(3), while (2) crystallizes in the monoclinic space group C2/c with a = 23.1981(15), b = 9.2959(4), c = 16.5505(11) angstrom, alpha = 90.00 degrees beta = 95.850(5)degrees, gamma = 90.00 degrees, Z = 8, V = 3550.5(4) angstrom(3). There are two distinct molecules with similar conformations in the asymmetric unit of (1). The imidazole and phenyl rings, forming the benzimidazole system are coplanar, and the bicyclic benzimidazole and the phenyl rings are essentially planar. The benzimidazole ring systems make dihedral angles of 28.97(0.08) and 49.29(0.06)degrees with the phenyl rings in (1) and (2), respectively. The structure of (1) is defined by weak aromatic pi-pi interactions and intermolecular hydrogen bonds, while there are no conventional hydrogen bonds in (2), and its crystal packing is dominated by van der Waal's and dipole-dipole interactions.