4-Nitro-N′-[(E)-3-pyridylmethylidene]benzohydrazide

In the title moleclue, C13H10N4O3, the methylidene–hydrazide [–C(=O)—N—N=C–] fragment is essentially planar, with a maximum deviation of 0.0228 (7) Å. The mean planes of the benzene and pyridine rings make dihedral angles of 25.44 (6) and 5.47 (7)°, respectively, with the mean plane of the methylidene–hydrazide fragment. In the crystal structure, intermolecular N—H⋯N hydrogen bonds link molecules into chains along the b axis. Additional stabilization is provided by weak intermolecular C—H⋯O hydrogen bonds. The O atoms of the nitro group are disordered over two sets of sites of equal occupancy.

In the title moleclue, C 13 H 10 N 4 O 3 , the methylidene-hydrazide [-C( O)-N-N C-] fragment is essentially planar, with a maximum deviation of 0.0228 (7) Å . The mean planes of the benzene and pyridine rings make dihedral angles of 25.44 (6) and 5.47 (7) , respectively, with the mean plane of the methylidene-hydrazide fragment. In the crystal structure, intermolecular N-HÁ Á ÁN hydrogen bonds link molecules into chains along the b axis. Additional stabilization is provided by weak intermolecular C-HÁ Á ÁO hydrogen bonds. The O atoms of the nitro group are disordered over two sets of sites of equal occupancy.
HLS is grateful to the Institute of Chemistry, University of the Punjab for financial support.
by the condensation of pyridine-3-carbaldehyde with p-nitrobenzohydrazide, and determined its crystal structure which is presented in this paper.
The structure of the title compound is presented in Fig. 1. The bond distances and angles agree with the cortresponding bond distances and angles reported in closely related compounds (Raj et al., 2008;Fun et al., 2008;Wang et al., 2008;Qiu et al., 2009). The methylidenehydrazide fragment C7/C8/N2/N3/O3 in the title compound is essentially planar with maximum deviation being 0.0228 (7) Å for both C7 and N2 atoms. The mean-planes of the benzene ring (C1-C6) and pyridine ring (C9-C13/N4) make dihedral angles of 25.44 (6) and 5.47 (7)°, respectively, with the mean-plane of the methylidene hydrazide fragment. The structure is stabilized by extensive hydrogen bonding; details have been provided in Table 1.

Experimental
A mixture of para-nitrobenzohydrazide (0.5 g, 2.76 mmoles), pyridine-3-carbaldehyde (0.26 ml, 2.76 mmoles), orthophosphoric acid (0.2 ml) and methanol (50.0 ml) was heated to reflux for a period of 3.5 hours followed by removal of the solvent under vacuum. The contents were allowed to cool and washed with cold methanol to yield the title compound. Crystals suitable for X-ray crystallographic studies were grown from a methanol solution of the title compound at room temperature by slow evaporation. Yield: 92%. M.p. 547 K.

Refinement
Though all the H atoms could be distinguished in the difference Fourier map the H-atoms bonded to C-atoms were included at geometrically idealized positions and refined in riding-model approximation with N-H = 0.88 Å and C-H = 0.95 Å; the U iso (H) were allowed at 1.2U eq (C/N). The final difference map was essentially featurless. The nitro group was disordered over two sites with N and O atoms occupying equal site occupancy factors, commands SIMU and EADP in SHELXL-97 (Sheldrick, 2008) were used to model the disorder. Fig. 1. The asymmetric unit of the title compound with the displacement ellipsoids plotted at 50% probability level (Farrugia, 1997); nitro group was disordered over two sites.

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.