(E)-N′-[1-(2-Hydroxyphenyl)ethylidene]-3-methoxybenzohydrazide

In the title compound, C16H16N2O3, the benzohydrazide group is not planar and the molecule exists in a trans configuration with respect to the methylidene unit. The dihedral angle between the two substituted benzene rings is 26.9 (2)°. In the crystal structure, the molecular packing is stabilized by intramolecular O—H⋯N and intermolecular N—H⋯O hydrogen bonds. The intermolecular hydrogen bonding forms chains parallel to the b axis.

In the title compound, C 16 H 16 N 2 O 3 , the benzohydrazide group is not planar and the molecule exists in a trans configuration with respect to the methylidene unit. The dihedral angle between the two substituted benzene rings is 26.9 (2) . In the crystal structure, the molecular packing is stabilized by intramolecular O-HÁ Á ÁN and intermolecular N-HÁ Á ÁO hydrogen bonds. The intermolecular hydrogen bonding forms chains parallel to the b axis.   Table 1 Hydrogen-bond geometry (Å , ).   (Zhong et al., 2007;Raj et al., 2007;Jimenez-Pulido et al., 2008). Due to the easy synthesis of such compounds, a great deal of hydrazones have been synthesized and structurally characterized (Yehye et al., 2008;Fun et al., 2008a,b;Yang et al., 2008;Ejsmont et al., 2008). Recently, we have reported two hydrazones (Ban & Li, 2008a,b). In this paper, we report herein the crystal structure of the title compound, (I). In the structure of (I), Fig. 1, the molecule exists in a trans configuration with respect to the methylidene unit. The dihedral angle between the two substituted benzene rings is 26.9 (2)°. In the 3-methoxyphenyl unit, the methoxy group is nearly coplanar with the mean plane of the C10-C15 ring, with the C16 atom deviates from the plane by 0.024 (2)

Experimental
The compound was prepared by refluxing 1-(2-hydroxyphenyl)ethanone (1.0 mol, 0136 g ) with 3-methoxybenzohydrazide (1.0 mol), 0166 g) in methanol (100 ml). Excess methanol was removed from the mixture by distillation. The colorless solid product was filtered, and washed three times with methanol. Colorless block crystals of the title compound were obtained from a methanol solution by slow evaporation in air.

Refinement
H2 was located in a difference Fourier map and refined isotropically, with N-H distance restrained to 0.90 (1) Å. Other H atoms were placed in calculated positions (C-H = 0.93 -0.96 Å, O-H = 0.82 Å) and refined as riding with U iso (H) = 1.2U eq (C) and 1.5U eq (O and methyl C). A rotating group model was used for the methyl groups.

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 > 2sigma(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.