4-Chloro-N′-(2-hydroxybenzylidene)benzohydrazide monohydrate

The asymmetric unit of the title compound, C14H11ClN2O2·H2O, contains a Schiff base molecule and a water molecule of crystallization. The dihedral angle between the two aromatic rings is 27.3 (4)°. In the crystal structure, molecules are linked into a two-dimensional network parallel to the bc plane by intermolecular O—H⋯O and N—H⋯O hydrogen bonds involving the water molecules.

The asymmetric unit of the title compound, C 14 H 11 ClN 2 O 2 Á-H 2 O, contains a Schiff base molecule and a water molecule of crystallization. The dihedral angle between the two aromatic rings is 27.3 (4) . In the crystal structure, molecules are linked into a two-dimensional network parallel to the bc plane by intermolecular O-HÁ Á ÁO and N-HÁ Á ÁO hydrogen bonds involving the water molecules.

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 comparable to the values observed in related compounds (Nie, 2008;He, 2008;Shi et al., 2007). The dihedral angle between the two aromatic rings in the Schiff base molecule is 27.3 (4)°. An intramolecular O-H···N hydrogen bond is observed.
In the crystal structure, the molecules are linked into a two-dimensional network parallel to the bc plane by intermolecular O-H···O and N-H···O hydrogen bonds (Table 1) involving the water molecules (Fig. 2).

Experimental
The title compound was prepared by the Schiff base condensation of salicylaldehyde (0.1 mol) and 4-chlorobenzohydrazide (0.1 mmol) in ethanol (50 ml). The excess ethanol was removed by distillation. The colourless solid formed was filtered and washed with ethanol. Single crystals suitable for X-ray diffraction were obtained by slow evaporation of 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 Å and O-H = 0.82Å] and refined using a riding model, with U iso (H) = 1.2U eq (C) and 1.5U eq (O1). Fig. 1

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.