N′-[(2-Hydroxy-1-naphthyl)methylidene]-2-nitrobenzohydrazide

In the title Schiff base compound, C18H13N3O4, prepared by the reaction of 2-hydroxy-1-naphthaldehyde with 2-nitrobenzohydrazide, the dihedral angle between the benzene ring and naphthyl ring system is 23.0 (2)°. There is an intramolecular O—H⋯N hydrogen bond involving the naphthalene hydroxy substituent and a hydrazide N atom. In the crystal structure, symmetry-related molecules are linked through intermolecular N—H⋯O hydrogen bonds, forming chains propagating in [101].

In the title Schiff base compound, C 18 H 13 N 3 O 4 , prepared by the reaction of 2-hydroxy-1-naphthaldehyde with 2-nitrobenzohydrazide, the dihedral angle between the benzene ring and naphthyl ring system is 23.0 (2) . There is an intramolecular O-HÁ Á ÁN hydrogen bond involving the naphthalene hydroxy substituent and a hydrazide N atom. In the crystal structure, symmetry-related molecules are linked through intermolecular N-HÁ Á ÁO hydrogen bonds, forming chains propagating in [101].

Experimental
Supplementary data and figures for this paper are available from the IUCr electronic archives (Reference: SU2174).

Comment
Schiff base compounds are a class of important materials used as pharmaceuticals and in various medicinal fields of interest (Dao et al., 2000;Sriram et al., 2006;Karthikeyan et al., 2006). 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 new Schiff base compounds have been reported Nadeem et al., 2009;Eltayeb et al., 2008). As a continuation of our work on such compounds (Hao, 2009a,b,c,d) we report herein on the crystal structure of a new title Schiff base compound, prepared by the reaction of 2-hydroxy-1-naphthyaldehyde with 2-nitrobenzohydrazide.
The molecular structure of the title compound is illustrated in Fig. 1. In the molecule there is an intramolecular O-H···N hydrogen bond, involving the naphthalene hydroxyl substituent and the hydrazide N-atom ( Fig.1 and Table 1). The molecule is twisted with the dihedral angle between the benzene and the naphthyl ring mean planes being 23.0 (2)°. All the bond lengths are within normal values (Allen et al., 1987).
In the crystal structure, symmetry related molecules are linked through intermolecular N-H···O hydrogen bonds, forming chains propagating in [101] (see Table 1 and Fig. 2).
Experimental 2-Hydroxy-1-naphthyaldehyde (0.1 mmol, 17.2 mg) and 2-nitrobenzohydrazide (0.1 mmol, 18.1 mg) in 30 ml of methanol were refluxed for 30 min to give a clear colourless solution. Colourless block-shaped single crystals of the title compound were formed by slow evaporation of the solvent over several days at room temperature.

Refinement
Hydrogen atom H2 was located in a difference Fourier map and refined isotropically, with the N-H distance restrained to 0.90 (1)Å, and U iso (H) restrained to 0.08 Å 2 . The other H-atoms were included in calculated positions and treated as riding 2U eq (C) and 1.5U eq (O).   Table 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.