(E)-N′-(2,4,5-Trifluorobenzylidene)isonicotinohydrazide monohydrate

In the Schiff base molecule of the title compound, C13H8F3N3O·H2O, the benzene ring and the pyridine ring are nearly coplanar, making a dihedral angle of 6.64 (7)°. The molecule exists in an E configuration with respect to the C=N double bond. In the crystal structure, molecules are linked via the water molecules into two-dimensional planes parallel to the ab plane through intermolecular N—H⋯O, O—H⋯O O—H⋯N and C—H⋯O hydrogen bonds.

In the Schiff base molecule of the title compound, C 13 H 8 F 3 N 3 OÁH 2 O, the benzene ring and the pyridine ring are nearly coplanar, making a dihedral angle of 6.64 (7) . The molecule exists in an E configuration with respect to the C=N double bond. In the crystal structure, molecules are linked via the water molecules into two-dimensional planes parallel to the ab plane through intermolecular N-HÁ Á ÁO, O-HÁ Á ÁO O-HÁ Á ÁN and C-HÁ Á ÁO hydrogen bonds.

Comment
In the search for new biologically active compounds, isoniazid (isonicotinylhydrazine) derivatives have been found to possess potential tuberculostatic activity (Janin, 2007;Maccari et al., 2005;Slayden & Barry, 2000). As part of our current work on the synthesis of (E)-N'-substituted isonicotinohydrazide derivatives, in this paper we present the crystal structure of the title compound, (I).
The asymmetric unit consists of one Schiff base molecule and one water molecule (Fig. 1). The geometric parameters are comparable to those related structures (Naveenkumar et al., 2009(Naveenkumar et al., , 2010Shi, 2005). The molecule is nearly coplanar with a dihedral angle between the benzene ring and the pyridine ring of 6.64 (7) Table 1).

Experimental
The isoniazid derivative was prepared following a procedure reported by Lourenco et al., (2008). 2,4,5-triflurobenzaldehyde (1.0 eq) was added to 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 was purified by washing with cold ethanol and diethyl ether to give the pure derivative. Colourless single crystals suitable for X-ray analysis were obtained by re-crystallization from methanol.

Refinement
All hydrogen atoms were located from the difference Fourier map and refined freely. Fig. 1. The molecular structure of (I) with atom labels and 50% probability ellipsoids for non-H atoms.

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 > 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.

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å 2 )
x y z U iso */U eq F1