N′-(2-Hydroxybenzylidene)-2-methoxybenzohydrazide monohydrate

In the title compound, C15H14N2O3·H2O, the Schiff base molecule is approximately planar, with a dihedral angle between the two aromatic rings of 10.2 (3)°. The molecular structure is stabilized by O—H⋯N and N—H⋯O hydrogen bonds. In the crystal structure, the Schiff base and water molecules are linked together by intermolecular O—H⋯O hydrogen bonds, forming chains parallel to the a axis.

In the title compound, C 15 H 14 N 2 O 3 ÁH 2 O, the Schiff base molecule is approximately planar, with a dihedral angle between the two aromatic rings of 10.2 (3) . The molecular structure is stabilized by O-HÁ Á ÁN and N-HÁ Á ÁO hydrogen bonds. In the crystal structure, the Schiff base and water molecules are linked together by intermolecular O-HÁ Á ÁO hydrogen bonds, forming chains parallel to the a axis.

Structure Reports Online
The asymmetric unit of the title compound consists of a Schiff base molecule and a water molecule of crystallization ( Fig. 1). The bond lengths are within normal values (Allen et al., 1987), and are comparable to the values observed in similar compounds (Nie, 2008;He, 2008;Shi et al., 2007). The dihedral angle between the two aromatic rings in the Schiff base molecule is 10.2 (3)°, indicating that the molecule is approximately coplanar. The molecular structure is stabilized by O-H···N and N-H···O hydrogen bonds.
In the crystal structure ( Fig. 2), the Schiff base and water molecules are linked into chains running parallel to the a axis by intermolecular O-H···O hydrogen bonds (Table 1).

Experimental
The title compound was prepared by the Schiff base condensation of salicylaldehyde (0.1 mol) and 2-methoxybenzohydrazide (0.1 mmol) in ethanol (50 ml). The excess ethanol was removed by distillation. The colourless solid obtained was filtered and washed with ethanol. Single crystals suitable for X-ray diffraction were grown by slow evaporation from an ethanol solution at room temperature.

Refinement
The imino and water H atoms were located in a difference map and refined with N-H, O-H, and H···H distances restrained to 0.90 (1), 0.85 (1), and 1.37 (2) Å, respectively. The other H atoms were positioned geometrically [C-H = 0.93-0.96 Å and O-H = 0.82 Å] and refined using a riding model, with U iso (H) = 1.2U eq (C) and 1.5U eq (C15 and O1). In the absence of significant anomalous scattering, Friedel pairs were merged.

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.