(1H-Benzimidazol-1-yl)methanol

In the title compound, C8H8N2O, the N—CH2 and CH2—O bond lengths can be correlated to the manifestation of an anomeric effect in the N—CH2—O moiety. In the crystal, intermolecular O—H⋯N hydrogen bonds link the molecules into zigzag chains, with graph-set motif C(6), parallel to [001]. These chains are further linked into sheets by weak nonclassical C—H⋯O hydrogen bonds.

In the title compound, C 8 H 8 N 2 O, the N-CH 2 and CH 2 -O bond lengths can be correlated to the manifestation of an anomeric effect in the N-CH 2 -O moiety. In the crystal, intermolecular O-HÁ Á ÁN hydrogen bonds link the molecules into zigzag chains, with graph-set motif C(6), parallel to [001]. These chains are further linked into sheets by weak nonclassical C-HÁ Á ÁO hydrogen bonds.

Related literature
For a related structure, see: Shi et al. (2011). For bond-length data, see: Allen et al. (1987). For chemical background on the synthesis and uses of the title compound, see: Milata et al. (2001). For graph-set analysis, see: Bernstein et al. (1995).  Table 1 Hydrogen-bond geometry (Å , ). Data collection: CrysAlis PRO (Agilent, 2010); cell refinement: CrysAlis PRO; data reduction: CrysAlis PRO; program(s) used to solve structure: SIR2002 (Burla et al., 2003); program(s) used to refine structure: JANA2006 (Petříček et al., 2006); molecular graphics: DIAMOND (Brandenburg & Putz, 2005); software used to prepare material for publication: JANA2006. In the title compound, C 8 H 8 N 2 O, (Fig.1) the benzimidazole ring is essentially planar, with a maximum deviation for N1 of 0.0089 (12)Å from the least-squares plane defined by the nine constituent atoms. The sum of bond angles around this nitrogen atom was 359.90 (11)°, which is consistent with the planarization of the heterocyclic ring. The distances within the benzimidazole ring of the title compound are very similar to those found in bis(1H-benzimidazol-1-yl)methane monohydrate (Shi et al., 2011). However, the observed N-CH 2 bond length [N1-C8, 1.4638 (17) Å] is longer in relation to the mentioned mean value observed in related structure [N-CH 2 , 1.452 (4) Å] (Shi et al., 2011). Moreover, the CH 2 -O bonds in the residue tend to be shorter than the normal values by 0.033 Å (Allen et al., 1987). This fact can be correlated to the manifestation of an anomeric effect in N-CH 2 -O moiety, but it operates in the opposite direction.In the crystal structure, intermolecular O-H···N hydrogen bonds link the molecules into zigzag chains with graph-set motif C(6) parallel to [001], (Bernstein et al., 1995) (Fig. 2). These chains are further linked into sheet by weak non-classical C -H···O hydrogen bonds between H atom of the benzimidazole ring and the O atom of a neighbouring molecule.

Experimental
A solution of 6H, 13H-5:12,7:14-dimethanedibenzo[d,i][1,3,6,8] tetraazecine (DMDBTA) (0.25 mmol) and p-nitrophenol (0.5 mmol) in propan-2-ol (15 ml) was placed in a round-bottomed flask equipped with a water-cooled condenser. The reaction mixture was heated at 347 K for 3 h. giving a white precipitate which was filtered off, and the mother liquor was then concentrated by a rotary evaporator to give an oil accompanied by precipitates, which was removed by filtration.
Single crystal of the precipitate (title compound), suitable for X-ray crystallography, was grown by slow evaporation from water:propan-2-ol solution at room temperature after several days. Melting point 407 K.

Refinement
The hydroxyl hydrogen atom was found in difference Fourier maps and its coordinates were refined freely. All other H atoms atoms were positioned geometrically and treated as riding on their parent atoms. The isotropic atomic displacement parameters of hydrogen atoms were evaluated as 1.2×U eq of the parent atom.

Figure 1
A view of the title molecule. Displacement ellipsoids are drawn at the 50% probability level.

Special details
Experimental. CrysAlisPro (Agilent , 2010) Empirical absorption correction using spherical harmonics, implemented in SCALE3 ABSPACK scaling algorithm. Refinement. The refinement was carried out against all reflections. The conventional R-factor is always based on F. The goodness of fit as well as the weighted R-factor are based on F and F 2 for refinement carried out on F and F 2 , respectively. The threshold expression is used only for calculating R-factors etc. and it is not relevant to the choice of reflections for refinement. The program used for refinement, Jana2006, uses the weighting scheme based on the experimental expectations, see _refine_ls_weighting_details, that does not force S to be one. Therefore the values of S are usually larger than the ones from the SHELX program.