(E)-N′-[(E)-2-Methylpent-2-enylidene]isonicotinohydrazide

The asymmetric unit of the title Schiff base compound, C12H15N3O, contains two crystallographically independent molecules, with both existing in an E configuration with respect to the C=N double bonds. In the crystal structure, intermolecular N—H⋯N and C—H⋯O hydrogen bonds link the molecules into a three-dimensional network.

The asymmetric unit of the title Schiff base compound, C 12 H 15 N 3 O, contains two crystallographically independent molecules, with both existing in an E configuration with respect to the C N double bonds. In the crystal structure, intermolecular N-HÁ Á ÁN and C-HÁ Á ÁO hydrogen bonds link the molecules into a three-dimensional network.

Comment
In the search of new compounds, isoniazid derivatives have been found to possess potential tuberculostatic activity (Janin, 2007;Maccari et al., 2005;Slayden et al., 2000). Schiff bases have attracted much attention because of their biological activity (Kahwa et al., 1986). As a part of a current work of synthesis of (E)-N'-substituted isonicotinohydrazide derivatives, in this paper we present the crystal structure of the title compound.

Experimental
The isoniazid derivative was prepared following the procedure by Lourenco et al. (2008). The titled compound was prepared by reaction between the 2-methyl-2-pentenal (1.0 eq) with isoniazid (1.0 eq) in ethanol/water. After stirring for 1-3 h at room temperature, the resulting mixture was concentrated under reduced pressure. The residue, purified by washing with cold ethanol and ethyl ether, afforded the pure derivative. The colourless single crystal suitable for X-ray analysis was obtained by recrystalization with methanol.
The remaining H atoms were positioned geometrically (C-H = 0.93-0.97 Å) and were refined using a riding model, with U iso (H) = 1.2 or 1.5 U eq (C). A rotating group model was applied to all the methyl groups. In the final difference Fourier map, the highest peak is 1.08 Å from atom H11E and the deepest hole is 0.59 Å from atom C9B. In the absence of significant anomalous dispersion, 2998 Friedel pairs were merged before the final refinement. Fig. 1. The molecular structure of the title compound, showing 50% probability displacement ellipsoids and the atom-numbering scheme.   Glazer, 1986) operating at 100.0 (1) K.

sup-2 Figures
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.