(±)-1-(1H-Benzimidazol-2-yl)ethanol

The asymmetric unit of the title molecule, C9H10N2O, contains two molecules. The fused benzene and imidazole rings are nearly coplanar, the largest deviations from the mean plane being 0.025 (3) Å at the non-bridgehead imidazole C atom of one molecule and 0.018 (3) Å at one of the bridgehead C atoms in the other molecule. Intermolecular O—H⋯N and N—H⋯O hydrogen bonds result in the formation of a sheet parallel to the (010) plane.

(±)-1-(1H-Benzimidazol-2-yl)ethanol R. Xia and H.-J. Xu Comment Imidazole and benzimidazole derivatives are important heteroaromatic compounds and have attracted considerable attention because of good biological and pharmaceutical activities (Matsuno et al., 2000;Garuti et al., 1999). These compounds also play an important role in the development of coordination chemistry. Many derivatives of benzimidazole have been prepared and their complexes have been studied (Tlahuext et al., 2007;Chen & Ruan, 2007). In this paper, we report the crystal structure of the title compound.
There are two crystallographically independent molecules, A and B, linked by a O-H···N hydrogen bond in the asymmetric unit . The bond lengths and angles in A and B are within normal ranges (Allen et al., 1987). The two fused benzene and imidazole rings are nearly planar with the largest deviations from the mean plane being 0.025 (3) Å at C7 and 0.018 (3) Å at C10 . These two fused rings make a dihedral angle of 35.01 (9)°.
The molecules are further connected through O-H···N and N-H···O hydrogen bond buiding up a two dimmensional network which is parallel to the (0 1 0) plane (Table 1, Fig. 2).
Only the relative absolute configuration could be determined, the C8 and C17 have the same absolute configuration (S,S) or (R,R). The (S,S) configuration is represented in Fig. 1.

Experimental
All chemicals were obtained from commercial sources and used directly without further purification. Benzene-1, 2-diamine (2.16 g, 20 mmol) was dissolved in hydrochloric acid (25 mL, 4 M) at 100°C, and ethyl 2-hydroxypropanoate (2.48 g, 21 mmol) was added to the solution. The mixture were then heated to reflux for 7 h at 115°C. After cooling to room temperature, the product was divided by neutralizing the mixture solution using NaOH to make the pH 7-9. Solid product was collected by filtration and the yield was 80%. In the absence of significant anomalous scattering, the absolute configuration could not be reliably determined and then the Friedel pairs were merged and any references to the Flack parameter were removed.

Special details
Geometry. All esds (except the esd in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell esds are taken into account individually in the estimation of esds in distances, angles and torsion angles; correlations between esds in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell esds is used for estimating esds 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 Rfactors(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.