1-(4-Methylbenzyl)-1H-benzimidazol-2(3H)-one

In the title compound, C15H14N2O, the fused five- and six-membered ring system is essentially planar, the maximum deviation from the mean plane being 0.009 (1) Å. The benzimidazol-2(3H)-one residue is nearly perpendicular to the benzyl ring, forming a dihedral angle of 77.41 (6)°. In the crystal, inversion dimers are formed by pairs of N—H⋯O hydrogen bonds; these dimers are linked by weak C—H⋯O interactions into a two-dimensional array in the (102) plane.

In the title compound, C 15 H 14 N 2 O, the fused five-and sixmembered ring system is essentially planar, the maximum deviation from the mean plane being 0.009 (1) Å . The benzimidazol-2(3H)-one residue is nearly perpendicular to the benzyl ring, forming a dihedral angle of 77.41 (6) . In the crystal, inversion dimers are formed by pairs of N-HÁ Á ÁO hydrogen bonds; these dimers are linked by weak C-HÁ Á ÁO interactions into a two-dimensional array in the (102) plane.
The crystal structure of the title compound, C 15 H 14 N 2 O, is built up from two fused five-and six-membered rings (C1-C7,N1,N2,O1) linked to (C8-C15) the p-methyl-benzyl residue as shown in Fig. 1. The fused-ring system is essentially planar, with the maximum deviation of 0.009 (1) Å for the N2 atom. The dihedral angle between the benzimidazol-2(3Hone system and the (C9 to C14) benzyl ring is 77.41 (6)°.

Experimental
To 1H-benzimidazol-2(3H)-one (0.2 g, 1.49 mmol), potassium carbonate (0.41 g, 3 mmol) and tetra-n-butylammonium bromide (0.05 g, 0.15 mmol) in DMF (15 ml) was added methyl benzyl bromide (0.33 g, 1.78 mmol). Stirring was continued at room temperature for 6 h. The salt was removed by filtration and the filtrate concentrated under reduced pressure. The residue was separated by chromatography on a column of silica gel with ethyl acetate/hexane (1/2) as eluent. The compound was recrystallized from hexane to give colorless crystals.

Figure 1
Molecular structure of the title compound with the atom-labelling scheme. Displacement ellipsoids are drawn at the 50% probability level. H atoms are represented as small circles.

Figure 2
Portion of the unit cell showing intermolecular interactions (dashed lines) as detailed in Table 1.  where P = (F o 2 + 2F c 2 )/3 (Δ/σ) max < 0.001 Δρ max = 0.17 e Å −3 Δρ min = −0.15 e Å −3 Extinction correction: SHELXL97 (Sheldrick, 2008), Fc * =kFc[1+0.001xFc 2 λ 3 /sin(2θ)] -1/4 Extinction coefficient: 0.0047 (19) Special details Geometry. All e.s.d.'s (except the e.s.d. in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell e.s.d.'s are taken into account individually in the estimation of e.s.d.'s in distances, angles and torsion angles; correlations between e.s.d.'s in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell e.s.d.'s is used for estimating e.s.d.'s involving l.s. planes. 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 > σ(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.