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

The title Schiff base compound, C14H12N4O3, displays an E conformation with respect to the C=N double bond [1.268 (3) Å]. The dihedral angle between the benzene rings is 3.2 (5)°, consistent with an essentially planar molecule. In the crystal, N—H⋯O and N—H⋯N hydrogen bonds, as well as C—H⋯O interactions, link the molecules into layers that stack along the c axis.

The title Schiff base compound, C 14 H 12 N 4 O 3 , displays an E conformation with respect to the C N double bond [1.268 (3) Å ]. The dihedral angle between the benzene rings is 3.2 (5) , consistent with an essentially planar molecule. In the crystal, N-HÁ Á ÁO and N-HÁ Á ÁN hydrogen bonds, as well as C-HÁ Á ÁO interactions, link the molecules into layers that stack along the c axis.
As shown in Fig. 1, the asymmetric unit of the title compound, (I), contains one independent molecule displaying an E configuration with respect to its C═N double bond. The dihedral angle between the two benzene rings is 3.2 (5)°. The bond lengths and angles are as expected for a compound of this type and agree with the other ligands belonging to the hydrazone series. The C8═N3 and C7═O1 bond lengths of 1.268 (3) and 1.226 (3) Å, respectively, are the expected values for such double bonds. In the crystal packing, it is noted that amino-H (H1A, H1B) and amide-H2A atoms are involved in forming intermolecular N-H···O and N-H···N hydrogen bonds ( Fig. 2 and Table 1), linking the molecules into a two-dimensional layer structure that stacks along the c axis. Weak C-H···O interactions are also noted within the layer.

Experimental
To a methanol solution (20 ml) of 2-nitrobenzaldehyde (1 mmol, 0.151 g) and 4-aminobenzohydrazide (1 mmol, 0.151 g), a few drops of acetic acid were added. The mixture was refluxed for 2 h and then cooled to room temperature to give a yellow solution. Crystals of the title compound were formed by gradual evaporation of the solvent over a period of 6 days at room temperature.

Refinement
H-atoms were placed in calculated positions (C-H = 0.93 and N-H = 0.86-0.89 Å) and were included in the refinement in the riding model approximation, with U iso (H) set to 1.2U eq (C or N). In the absence of significant anomalous scattering effects, 1120 Friedel pairs were averaged in the final refinement.

Figure 2
Crystal packing in the title compound where molecules are linked via N-H···O and N-H···N hydrogen bonds (dashed lines). Except for those involved in hydrogen-bonding interactions, H atoms have been omitted for clarity. 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.

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å 2 )
x y z U iso */U eq O1 0.6908 (