(E)-2-Methoxy-N′-(4-nitrobenzylidene)benzohydrazide

In the title compound, C15H13N3O4, the molecule exists in a trans configuration with respect to the methylidene unit. The dihedral angle between the two benzene rings is 6.8 (2)°. The C—N—NH—C torsion angle is 3.4 (3)°. The molecule possesses an intramolecular N—H⋯O hydrogen bond. In the crystal structure, adjacent molecules are linked through intermolecular C—H⋯O hydrogen bonds, forming dimers

In the title compound, C 15 H 13 N 3 O 4 , the molecule exists in a trans configuration with respect to the methylidene unit. The dihedral angle between the two benzene rings is 6.8 (2) . The C-N-NH-C torsion angle is 3.4 (3) . The molecule possesses an intramolecular N-HÁ Á ÁO hydrogen bond. In the crystal structure, adjacent molecules are linked through intermolecular C-HÁ Á ÁO hydrogen bonds, forming dimers
Hydrazones derived from the condensation of aldehydes with hydrazides have been shown to possess excellent biological activities (Zhong et al., 2007;Raj et al., 2007;Jimenez-Pulido et al., 2008). Due to the easy synthesis of such compounds, a great deal of hydrazones have been synthesized and structurally characterized (Yehye et al., 2008;Fun, Patil, Jebas et al., 2008;Fun, Patil, Rao et al., 2008;Yang et al., 2008;Ejsmont et al., 2008). Recently, we have also reported the crystal structures of a few hydrazones (Ban & Li, 2008a,b;Li & Ban, 2009a,b). In this paper, we report the crystal structure of the title compound.
In the structure of the title compound ( Fig. 1) the molecule exists in a trans configuration with respect to the methylidene unit. The dihedral angle between the two benzene rings is 6.8 (2)°. In the 2-methoxyphenyl unit, the methoxy group is nearly coplanar with the mean plane of the C9-C14 ring; the atom C15 deviates from this plane by 0.002 (2) Å. The torsion angle The molecule possesses an intramolecular N-H···O hydrogen bond (Table 1, Fig. 1).

Experimental
The compound was prepared by refluxing 4-nitrobenzaldehyde (1.0 mol) with 2-methoxybenzohydrazide (1.0 mol) in methanol (100 ml). Excess methanol was removed from the mixture by distillation. The colorless solid product was filtered, and washed three times with methanol. Colorless block crystals of the title compound were obtained from a methanol solution by slow evaporation in air.

Refinement
H2A, attached to N2, was located in a difference Fourier map and refined isotropically, with the N-H distance restrained to 0.90 (1) Å. Other H atoms were placed in calculated positions (C-H = 0.93 -0.96 Å) and refined as riding with U iso (H) = 1.5U eq (methyl C) and 1.2U eq (other C). A rotating group model was used for the methyl group.
Figures Fig. 1. The molecular structure of the title compound, showing 30% probability displacement ellipsoids for the non-hydrogen atoms. Hydrogen atoms are shown as spheres of arbitrary radius. The intramolecular N-H···O hydrogen bond is shown as a dashed line.

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.