2-Methoxybenzaldehyde 2,4-dinitrophenylhydrazone

In the title compound, C14H12N4O5, an intramolecular N—H⋯O hydrogen bond generates an S(6) ring motif. The dihedral angle between the two benzene rings is 3.91 (3)°, which shows the molecule is almost planar. The para-nitro group is twisted from the benzene ring to which it is attached, making a dihedral angle of 8.50 (9)°. In the crystal structure, molecules are linked together by intermolecular C—H⋯O and intermolecular three-centred O⋯O [2.8646 (12)–2.9213 (11) Å] and O⋯N [3.0518 (11) Å] interactions. The crystal structure is further stabilized by intermolecular π–π interactions [centroid-to-centroid distances 3.5708 (6)–3.9728 (12) Å].

Bond lengths in the title compound ( Fig. 1) are normal (Allen et al., 1987). An intramolecular N-H···O hydrogen bond generates an S(6) ring motif (Bernstein et al., 1995). The molecule is nearly planar, with a maximum deviation from the mean plane of -0.3464 (8) Å for atom O4 which is due to the intermolecular three-centered O···O and O···N interactions.

Experimental
The title compound was synthesized based on the reported procedure (Okabe et al. 1993) except that 3-methoxybenzaldehyde (1 mmol, 136 mg) 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 ethanol.

Refinement
N-bound H atom was located from the difference Fourier map and refined freely. The remaining H atoms were placed in calculated positions (C-H = 0.93-0.96 Å) and refined using a riding model, with U iso (H) = 1.2 or 1.5U eq (C). A rotating group model was applied to the methyl group. Fig. 1. The molecular structure of the title compound, showing 50% probability displacement ellipsoids and the atomic numbering scheme. Hydrogen bond is shown as a dashed line.

Special details
Experimental. The low-temperature data was collected with the Oxford Cyrosystem Cobra low-temperature attachment.
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.