1-(Butan-2-ylidene)-2-(2-nitrophenyl)hydrazine

Crystals of the title compound, C10H13N3O2, were obtained from a condensation reaction of butan-2-one and 1-(2-nitrophenyl)hydrazine. The molecule exhibits a nearly coplanar structure, except for the methyl and methylene H atoms, the largest deviations from the mean plane defined by all non-H atoms, except for the nitro group, being 0.120 (2) Å for one of the nitro O atoms. Intramolecular N—H⋯O hydrogen bonding helps to establish the molecular configuration.

Crystals of the title compound, C 10 H 13 N 3 O 2 , were obtained from a condensation reaction of butan-2-one and 1-(2nitrophenyl)hydrazine. The molecule exhibits a nearly coplanar structure, except for the methyl and methylene H atoms, the largest deviations from the mean plane defined by all non-H atoms, except for the nitro group, being 0.120 (2) Å for one of the nitro O atoms. Intramolecular N-HÁ Á ÁO hydrogen bonding helps to establish the molecular configuration.

Comment
The chemistry of Schiff base has attracted a great deal of interest in recent years. These compounds play an important role in the development of various proteins and enzymes (Kahwa et al., 1986;Santos et al., 2001). As part of our in the study of the coordination chemistry of Schiff bases, we synthesized the title compound and determined its crystal structure.
The molecular structure of (I) is shown in Fig. 1. The molecules is roughly planar, with the largest deviations from the mean plane defined by all non-H atoms, except the nitro group, being -0.120 (2) for atom O2.
Intramolecular N-H···O hydrogen bond is observed in compound (I), and this helps to stabilize the configuration of the molecule.
Experimental 2-Nitrophenylhydrazine (1 mmol, 0.153 g) was dissolved in anhydrous ethanol (15 ml). The mixture was stirred for several min at 351 K, then butan-2-one (1 mmol, 0.72 g) in ethanol (8 ml) was added dropwise and the mixture was stirred at refluxing temperature for 2 h. The product was isolated and recrystallized from methanol, red single crystals were obtained after 3 d.

Refinement
Imino H atom was located in a difference Fourier map and positional parameters were refined with a fixed isotropic thermal parameter of 0.08 Å 2 . Other H atoms were positioned geometrically and refined as riding with C-H = 0.93 (aromatic), 0.97 (methylene) and 0.96 Å (methyl), with U iso (H) = 1.5U eq (C) for methyl H atoms and 1.2U eq (C) for the others.

Special details
Geometry. All e.s.d.'s (except the e.s.d. in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell e.s.d.'s are taken into account individually in the estimation of e.s.d.'s in distances, angles and torsion angles; correlations between e.s.d.'s in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell e.s.d.'s is used for estimating e.s.d.'s 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 > σ(F 2 ) is used only for calculating Rfactors(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.