N′-(But-2-enylidene)isonicotinohydrazide

In the title Schiff base compound, C10H11N3O, the pyridine ring is twisted with respect to the mean plane containing the hydrazine chain, making a dihedral angle of 31.40 (9)°. The NH group interacts with the N atom of the pyridine ring through N—H⋯N hydrogen bonds to build up a zigzag chain developing parallel to the (01) plane.

In the title Schiff base compound, C 10 H 11 N 3 O, the pyridine ring is twisted with respect to the mean plane containing the hydrazine chain, making a dihedral angle of 31.40 (9) . The NH group interacts with the N atom of the pyridine ring through N-HÁ Á ÁN hydrogen bonds to build up a zigzag chain developing parallel to the (101) plane.

Comment
The chemistry of Schiff bases 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 interest in the study of the coordination chemistry of Schiff bases, we have synthesized the title compound (I) and reported its cyrstal structure.
In the title compound. the pyridine ring is twisted with respect to the mean plane containing the hydrazine chain making a dihedral angle of 31.40 (9)° (Fig. 1). The NH interacts with the nitrogen atom of the pyridine ring through N-H···N hydrogen bond to build up a zig-zag chain developing parallel to the (-1 0 1) plane (Table 1, Fig. 2).

Experimental
Pyridine-4-carboxylic acid hydrazide (1 mmol, 0.137 g) was dissolved in anhydrous methanol, H 2 SO 4 (98% 0.5 ml) was added to this, the mixture was stirred for several minitutes at 351 K, 3,4-dichlorobenzyaldehyde (1 mmol 0.070 g) in methanol (8 ml) was added dropwise and the mixture was stirred at refluxing temperature for 2 h. The product was isolated and recrystallized in dichloromethane, brown single crystals of (I) was obtained after 5 d.
In the absence of significant anomalous scattering, the absolute structure could not be reliably determined and then the Friedel pairs were merged and any references to the Flack parameter were removed.

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 > 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.