N-(2,4-Dinitrophenyl)-N′-(1-p-tolylethylidene)hydrazine

In the title molecule, C15H14N4O4, the dihedral angle between the two benzene rings is 2.21 (7)°. An intramolecular N—H⋯O hydrogen bond generates an S(6) ring motif. The mean planes of the ortho- and para-nitro groups make dihedral angles of 2.17 (17) and 2.05 (16)°, respectively, with the benzene ring to which they are attached. In the crystal structure, weak intermolecular C—H⋯O hydrogen bonds generate R 2 2(7), R 2 2(13) and R 2 1(10) ring motifs, linking symmetry-related molecules into extended chains along the b axis. In addition, there are intermolecular C⋯C [3.332 (2)–3.343 (2) Å] contacts which are shorter than the sum of the van der Waals radii. The crystal structure is further stabilized by intermolecular C—H⋯π and π–π stacking interactions [centroid–centroid distance = 3.8090 (9) Å].

The bond lengths (Allen et al., 1987) and angles in the title compound ( Fig. 1) have normal values and are comparable to the related structures Kia et al. 2009). An intramolecular N-H···O hydrogen bond generates a S(6) ring motif (Bernstein et al., 1995). Weak intermolecular C-H···O hydrogen bonds generate R 2 2 (7), R 2 2 (13) and R 2 1 (10) ring motifs. These interactions link symmetry related molecules into extended chains along the b axis (Fig. 2). The molecule is approximately planar, with the maximum deviation from the mean plane of the molecule being 0.381 (2) Å for atom C14.

Experimental
The title compound was synthesized based on the reported procedure (Okabe et al. 1993) except that 4-methyl-acetophenone (1 mmol) was used instead. Single crystals suitable for X-ray diffraction analysis were grown by slow evaporation of a saturated solution of the resulted compound in acetone.

Refinement
The N-bound H atom was located from the difference Fourier map and refined freely; see, Table 1. The remaining H atoms were positined geometrically and constrained with a riding model approximation with C-H = 0.93-0.96 Å and U iso (H) = 1.2 or 1.5 U eq (C). A rotating group model was applied to the methyl groups.

Special details
Experimental. The crystal was placed in the cold stream of an Oxford Cyrosystems Cobra open-flow nitrogen cryostat (Cosier & Glazer, 1986) operating at 100.0 (1)K.
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.