(E)-N′-(4-Hydroxybenzylidene)-2-nitrobenzohydrazide

In the title compound, C14H11N3O4, the two benzene rings form a dihedral angle of 45.3 (3)°. The nitro group is twisted out of the attached ring by a dihedral angle of 37.5 (3)°. In the crystal structure, molecules are linked into a two-dimensional network parallel to (100) by O—H⋯O and N—H⋯O hydrogen bonds.


Comment
Considerable attention has been focused on hydrazones and their medicinal applications (Hillmer et al., 2010;Zhu et al., 2009;Jimenez-Pulido et al., 2008;Raj et al., 2007;Zhong et al., 2007). The study on the crystal structures of such compounds is of particular interest (Khaledi et al., 2009;Warad et al., 2009;Back et al., 2009;Vijayakumar et al., 2009). We report herein the crystal structure of the title new hydrazone.
In the title molecule ( Fig. 1), the dihedral angle between the two benzene rings is 45.3 (3)°, indicating that the molecule is twisted. The dihedral angle between the N3/O3/O4 nitro group and the C9-C14 benzene ring is 37.5 (3)°. All the bond lengths are comparable to those observed in related structures (Cao, 2009;Xu et al., 2009;Shafiq et al., 2009).
In the crystal structure, molecules are linked through O-H···O and N-H···O hydrogen bonds, to form a two-dimensional network parallel to the (100) (Fig. 2 and Table 1).

Experimental
The title compound was prepared by the condensation reaction of 4-hydroxybenzaldehyde (0.05 mol, 6 g) and 2-nitrobenzohydrazide (0.05 mol, 9 g) in anhydrous methanol (200 ml) at ambient temperature. Colourless block-shaped single crystals suitable for X-ray structure determination were obtained by slow evaporation of the methanol solution for a period of 8 d.

Refinement
Atom H2A was located in a difference map and refined isotropically, with the N-H distance restrained to 0.90 (1) Å [U iso (H2) = 0.08 Å 2 ]. The remaining H atoms were placed in idealized positions and constrained to ride on their parent atoms, with C-H distances of 0.93 Å, O-H distance of 0.82 Å, and with U iso (H) = 1.2U eq (C) and 1.5U eq (O). In the absence of significant anomalous dispersion effects, Friedel pairs were averaged. Fig. 1. The molecular structure of the title compound. Displacement ellipsoids are drawn at the 30% probability level. Hydrogen atoms are shown as spheres of arbitrary radius.

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.