2-(2-Hydroxybenzylideneamino)benzonitrile

The molecule of the title compound, C14H10N2O, displays a trans configuration with respect to the C=N double bond. The molecule is roughly planar; the two aromatic rings make a dihedral angle of 9.3 (3)°. Such a planar conformation is induced by the strong intramolecular O—H⋯N hydrogen bond between the imine and hydroxyl groups.

The molecule of the title compound, C 14 H 10 N 2 O, displays a trans configuration with respect to the C N double bond. The molecule is roughly planar; the two aromatic rings make a dihedral angle of 9.3 (3) . Such a planar conformation is induced by the strong intramolecular O-HÁ Á ÁN hydrogen bond between the imine and hydroxyl groups.
HJX acknowledges a Start-up Grant from Southeast University.
Supplementary data and figures for this paper are available from the IUCr electronic archives (Reference: DN2331).

Comment
The Schiff base compounds have received considerable attention for several decades, primarily due to their importance in the development of coordination chemistry related to magnetism (Weber, et al., 2007), catalysis (Chen, et al., 2008) and biological process (May, et al.,2004). Recently, we have reported a Schiff base compound (Xu, et al., 2008). As an extention of our work on the structural characterization of Schiff base compounds, the title compound, (I), has been synthesized and its crystal structure is reported here.
As expected, the molecule displays a trans configuration about the central C7=N1 bond. The dihedral angle between the planes of the two aromatic rings is 9.34(0.29)°, showing that the conjugated part of the molecule is not entirely coplanar. A strong O -H ··· N intramolecular hydrogen-bond interaction is observed in the molecular structure ( Fig. 1, Table 1) similar to the pervious reports (Xu et al., 2008;Cheng et al.,2006Cheng et al., , 2005. All the bond lengths and bond angles in the compound are within normal ranges (Allen, et al., 1987). The C7=N1 bond length of 1.292 (5) Å indicates a high degree of double-bond character comparable with the corresponding bond lengths in other Schiff bases (1.280 (2) Å; Elmah et al., 1999).

Experimental
All chemicals were obtained from commercial sources and used without further purification except for salicylaldehyde which is distiled under reduced pressure before use. 3-aminobenzonitrile (1.18 g, 10 mmol) and salicylaldehyde (1.22 g, 10 mmol) were dissolved in ethanol (20 ml). The mixture was heated to reflux for 4 h, then cooled to room temperature overnight and large amounts of a yellow precipitate were formed. Yellow crystal was obtained by recrystallization from ethyl alcohol(yield: 85%). 1 H-NMR(CDCl 3 , 300 MHz): δ6.98 (t, 1 H), 7.08 (d, 1 H), 7.37(t, 2 H), 7.45 (t, 2 H), 7.69 (m, 2H), 8.72 (s, 1 H). Esi-MS: calcd for C 14 H 9 N 2 O -H m/z 221.24, found 221.34. For the X-ray diffraction analysis, suitable single crystals of compound (I) were obtained after one week by slow evaporation from an ethyl alcohol solution.

Refinement
All H atoms attached to C atoms and O atom were fixed geometrically and treated as riding with C-H = 0.93 Å and O-H = 0.82Å with U iso (H) = 1.2U eq (C) or U iso (H) = 1.5U eq (O).
In the absence of significant anomalous scattering, the absolute structure 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.