2-[4-(Trifluoromethoxy)phenyl]-1H-benzimidazole

In the title compound, C14H9F3N2O, the best planes of the benzimidazole group and benzene ring form a dihedral angle of 26.68 (3)°. In the crystal, N—H⋯N hydrogen bonds link the molecules into infinite chains parallel to the c axis. Stacking interactions between the benzimidazole groups [centroid–centroid distance = 3.594 (5) Å] assemble the molecules into layers parallel to (100). The trifluoromethyl group is disordered over three sets of sites with site-occupancy factors of 0.787 (4), 0.107 (7) and 0.106 (7).


Related literature
NSB is thankful to the University Grants Commission (UGC), India, for financial assistance.

Experimental
A mixture of 4-(trifluoromethoxy)benzaldehyde (10 mmol, 0.19 g) and o-phenyldiamine (10 mmol, 0.19 g) in benzene (2 ml) was refluxed for 6 h on a water bath. The reaction mixture was cooled. The solid separated, was filtered and dried (yield: 0.26 g, 75% and m.p. 503-508 K). Pale yellow crystals of the title compound were obtained by slow evaporation from a solution in ethyl acetate.

Refinement
All H atoms were included in calculated positions, with C-H bond distances of 0.93 Å and N-H = 0.86 Å and refined in a riding model approximation with U iso (H) = 1.2U eq (C,N). The trifluoromethyl group is disordered over three sites with the occupancy factors 0.787 (4), 0.107 (7) and 0.106 (7). The atoms of the minor components were refined isotropically with a common displacement parameter for each group. The geometry of the minor components was restrained to that of the major component with the SAME instruction of SHELXL97 (Sheldrick, 2008).  The molecular structure of the title compound with the atom numbering scheme. Displacement ellipsoids are drawn at the 50% probability level. H atoms are presented as small spheres of arbitrary radius.The trifluoromethyl group is disordered over three sites.

Figure 2
A view of the intermolecular hydrogen bonds(dotted lines) in the crystal structure of the title compound. H atoms non participating in H-bonding and minor components of the disordered CF 3 group were omitted for clarity. where P = (F o 2 + 2F c 2 )/3 (Δ/σ) max = 0.001 Δρ max = 0.26 e Å −3 Δρ min = −0.22 e Å −3 Special details Geometry. All s.u.'s (except the s.u. in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell s.u.'s are taken into account individually in the estimation of s.u.'s in distances, angles and torsion angles; correlations between s.u.'s in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell s.u.'s is used for estimating s.u.'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 > 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.

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å 2 )
x y z U iso */U eq Occ. (