1,2-Diphenyl-1H-benzimidazole

In the title molecule, C19H14N2, the benzimidazole unit is close to being planar [maximum deviation = 0.0102 (6) Å] and forms dihedral angles of 55.80 (2) and 40.67 (3)° with the adjacent phenyl rings; the dihedral angle between the phenyl rings is 62.37 (3)°. In the crystal, one C—H⋯N hydrogen bond and three weak C—H⋯π interactions involving the fused benzene ring and the imidazole ring are observed, leading to a three-dimensional architecture.

Supplementary data and figures for this paper are available from the IUCr electronic archives (Reference: HG5265).

Butcher Comment
Fused imidazole derivatives such as benzoimidazoles and phenanthroimidazoles [Fang et al., (2007), Ge et al., (2008), Lai et al., (2008)] have been used in the fabrication of light-emitting devices, employing them as electron-transporting layer and as sensitizers in dye-sensitized solar cells [Shin et al., (2007), Tsai et al., (2007)] due to their wide optical absorption, bright luminescence and bipolar transport characteristics. Since our research group is working in organic light emitting devices, we are interested to use the title compound as ligand for synthesizing Ir(III) complexes. Jayamoorthy et al., (2012) have reported a closely related crystal structure of 2-(4-Fluorophenyl)-1-phenyl-1H-benzimidazole.
In the title molecule, C 19 H 14 N 2 (Fig. 1), the benzimidazole unit is almost planar [maximum deviation = 0.0102 (6) Å for C2]. The dihedral angles between the planes of the benzimidazole and the phenyl ring at N1 and the phenyl at C2 are 55.80 (2) and 40.67 (3)°, respectively. The dihedral angle between the planes of the adjacent phenyl rings is 62.37 (3)°.

Experimental
The pure N-phenyl-o-phenylenediamine (3.128 g, 17 mmol) in ethanol (10 ml), benzaldehyde (1.72 ml, 17 mmol) and ammonium acetate (3 g) was added about 1 h by maintaining the temperature at 353 K. The reaction mixture was refluxed for appropriate time and the completion of reaction was monitored by TLC, finally the reaction extracted with dichloromethane. The solid separated was purified by column chromatography using petroleum ether: ethyl acetate as the eluent. Yield: 2.49 g (50%). The title compound was dissolved in acetonitrile and allowed to slow evaporation for two days 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 Å. U iso (H) = 1.2U eq (C).

Computing details
Data collection: CrysAlis PRO (Agilent, 2012); cell refinement: CrysAlis PRO (Agilent, 2012); data reduction: CrysAlis PRO (Agilent, 2012); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: ORTEP-3 (Farrugia, 1997) and PLATON (Spek, 2009); software used to prepare material for publication: PLATON (Spek, 2009     where P = (F o 2 + 2F c 2 )/3 (Δ/σ) max = 0.001 Δρ max = 0.52 e Å −3 Δρ min = −0.25 e Å −3 Special details Geometry. Bond distances, angles etc. have been calculated using the rounded fractional coordinates. All su's are estimated from the variances of the (full) variance-covariance matrix. The cell e.s.d.'s are taken into account in the estimation of distances, angles and torsion angles Refinement. Refinement of F 2 against ALL reflections. The weighted R-factor wR and goodness of fit S are based on F 2 , conventional R-factors R are based on F, with F set to zero for negative F 2 . The threshold expression of F 2 > 2σ(F 2 ) is used only for calculating R-factors(gt) etc. and is not relevant to the choice of reflections for refinement. R-factors based on F 2 are statistically about twice as large as those based on F, and R-factors based on ALL data will be even larger.