1-(4-Methylbenzyl)-2-(4-methylphenyl)-1H-benzimidazole

The title compound, C22H20N2, crystallizes with two independent molecules (A and B) in the asymmetric unit. The benzimidazole units are almost planar [maximum deviations = 0.0161 (8) Å for A and 0.0276 (8) Å for B]. The dihedral angles between the benzimidazole unit and the benzene rings of the 4-methylbenzyl and 4-methylphenyl groups are 76.64 (3) and 46.87 (4)°, respectively, in molecule A. The corresponding values in molecule B are 86.31 (2) and 39.14 (4)°. The dihedral angles between the planes of the two benzene rings are 73.73 (3) and 80.69 (4)° in molecules A and B, respectively. Pairs of weak intermolecular C—H⋯N hydrogen bonds link B molecules, forming centrosymmetric dimers with R 2 2(8) ring motifs. There are no significant corresponding interactions involving the A molecules.

The title compound, C 22 H 20 N 2 , crystallizes with two independent molecules (A and B) in the asymmetric unit. The benzimidazole units are almost planar [maximum deviations = 0.0161 (8) Å for A and 0.0276 (8) Å for B]. The dihedral angles between the benzimidazole unit and the benzene rings of the 4-methylbenzyl and 4-methylphenyl groups are 76.64 (3) and 46.87 (4) , respectively, in molecule A. The corresponding values in molecule B are 86.31 (2) and 39.14 (4) . The dihedral angles between the planes of the two benzene rings are 73.73 (3) and 80.69 (4) in molecules A and B, respectively. Pairs of weak intermolecular C-HÁ Á ÁN hydrogen bonds link B molecules, forming centrosymmetric dimers with R 2 2 (8) ring motifs. There are no significant corresponding interactions involving the A molecules.   Table 1 Hydrogen-bond geometry (Å , ). JJ is thankful to the Department of Science and Technology (No. SR/S1/IC-73/2010) and the University Grants Commission [F. No. 36-21/2008 (SR)] for providing funds for this research.

Related literature
zyl)-2-(4-chlorophenyl)-1H-benzimidazole. Benzimidazole ligands are used to prepare iridium complexes which have electroluminescent properties and are highly efficient phosphorescent materials (Li et al., 2009). Since our group is doing research in organic light emitting devices (OLED's), we are interested in using the title compound as a ligand in the preparation of Ir(III) complexes and in studying the photophysical properties of these complexes.
The title compound, C 22 H 20 N 2 , crystallizes with two independent molecules (A and B) in the asymmetric unit. The benzimidazole units are almost planar [maximum deviations = 0.0161 (8) for N1A and 0.0276 (8) Å for C2B]. The dihedral angles between the planes of the benzimidazole and the benzene rings of the 4-methylbenzyl and the p-tolyl groups are 76.64 (3) and 46.87 (4)°, respectively, in molecule A. The corresponding values in molecule B are 86.31 (2) and 39.14 (4)°. The dihedral angle between the planes of the two benzene rings is 73.73 (3) and 80.69 (4)° in molecules A and B, respectively.

Experimental
The pure o-phenylenediamine (1.62 g, 15 mmol) in ethanol (10 ml), ammonium acetate (1.66 g, 15 mmol) and p-tolualdehyde (1.6 g, 15 mmol) was added over about 1 h by maintaining the temperature at 353 K. The reaction mixture was refluxed for 5 days and extracted with dichloromethane. The obtained solid was purified by column chromatography using hexane:ethyl acetate as the eluent. Yield: 1.91 g (40%). The compound was dissolved in acetonitrile and the solution was allowed to evaporate slowly at room temperature to obtain crystals suitable for X-ray diffraction studies.

Refinement
The H atoms were positioned geometrically and allowed to ride on their parent atoms, with C-H = 0.93, 0.96 and 0.97 Å for Csp 2 , methyl and methylene H atoms, respectively. U iso (H) = xU eq (C), where x = 1.5 for methyl H atoms and 1.2 for other C-bound H atoms. All of the methyl groups were found to be disordered over two positions. They were refined as an idealized disordered methyl groups with equal occupancy of the two orientations.     (