N′-(5-Chloro-2-hydroxybenzylidene)-2-methoxybenzohydrazide

The title Schiff base compound, C15H13ClN2O3, was prepared by the reaction of equimolar quantities of 5-chloro-2-hydroxybenzaldehyde with 2-methoxybenzohydrazide in a methanol solution. The dihedral angle between the two benzene rings is 20.6 (3)°. An intramolecular O—H⋯N hydrogen bond may influence the molecular conformation. In the crystal structure, molecules form chains along the b direction via intermolecular N—H⋯O hydrogen bonds which are bifurcated involving an intramolecular N—H⋯O hydrogen bond.

The title Schiff base compound, C 15 H 13 ClN 2 O 3 , was prepared by the reaction of equimolar quantities of 5-chloro-2-hydroxybenzaldehyde with 2-methoxybenzohydrazide in a methanol solution. The dihedral angle between the two benzene rings is 20.6 (3) . An intramolecular O-HÁ Á ÁN hydrogen bond may influence the molecular conformation. In the crystal structure, molecules form chains along the b direction via intermolecular N-HÁ Á ÁO hydrogen bonds which are bifurcated involving an intramolecular N-HÁ Á ÁO hydrogen bond.
Supplementary data and figures for this paper are available from the IUCr electronic archives (Reference: LH5065).

Comment
Schiff base compounds are a class of important materials used as pharmaceutical and medicinal fields (Sriram et al., 2006;Karthikeyan et al., 2006;Dao et al., 2000). Schiff bases have also been used as versatile ligands in coordination chemistry (Ali et al., 2008;Kargar et al., 2009;Yeap et al., 2009). Recently, the crystal structures of a large number of Schiff base compounds bearing the hydrazone groups have been reported Nadeem et al., 2009;Eltayeb et al., 2008). As a continuous work (Hao, 2009a,b,c,d;Hao, 2010), in this paper, the title Schiff base compound, Fig. 1, is reported.
In the title compound, the dihedral angle between the two benzene rings is 20.6 (3)°. All the bond lengths are within normal values (Allen et al., 1987).
In the crystal structure, molecules are linked through intermolecular N-H···O hydrogen bonds (Table 1), forming chains along the b direction (Fig. 2).
Experimental 5-Chloro-2-hydroxybenzaldehyde (0.1 mmol, 15.6 mg) and 2-methoxybenzohydrazide (0.1 mmol, 16.6 mg) were refluxed in a 30 ml methanol solution for 30 min to give a clear colorless solution. Colorless block-shaped single crystals of the compound were formed by slow evaporation of the solvent over several days at room temperature.

Refinement
H2A was located from a difference Fourier map and refined isotropically, with the N-H distance restrained to 0.90 (1)Å, and with U iso fixed at 0.08Å 2 . Other H atoms were constrained to ideal geometries, with d(C-H) = 0.93-0.96Å, d(O-H) = 0.82Å, and with U iso (H) = 1.2U eq (C) and 1.5U eq (O and C15).

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.