(2E)-N′-[(E)-4-Chlorobenzylidene]-3-phenylprop-2-enohydrazide monohydrate

The conformation about each of the imine and ethene bonds in the title hydrazide hydrate, C16H13ClN2O·H2O, is E. The hydrazide molecule is approximately planar (r.m.s. deviation of the 20 non-H atoms = 0.172 Å). The most significant twist occurs about the ethene bond [C—C=C—C = 164.1 (5)°] and the dihedral angle formed between the benzene rings is 5.3 (2)°]. In the crystal, the presence of N—H⋯Ow and O—H⋯Oc (× 2; w = water and c = carbonyl) hydrogen bonds leads to a supramolecular array in the bc plane.

The conformation about each of the imine and ethene bonds in the title hydrazide hydrate, C 16 H 13 ClN 2 OÁH 2 O, is E. The hydrazide molecule is approximately planar (r.m.s. deviation of the 20 non-H atoms = 0.172 Å ). The most significant twist occurs about the ethene bond [C-C C-C = 164.1 (5) ] and the dihedral angle formed between the benzene rings is 5.3 (2) ]. In the crystal, the presence of N-HÁ Á ÁO w and O-HÁ Á ÁO c (Â 2; w = water and c = carbonyl) hydrogen bonds leads to a supramolecular array in the bc plane.
The use of the EPSRC X-ray crystallographic service at the University of Southampton, England, and the valuable assistance of the staff there is gratefully acknowledged. JLW acknowledges support from CAPES (Brazil). Otwinowski, Z. & Minor, W. (1997)  Comment Tuberculosis (TB) remains among the world's great public health challenges. Worldwide resurgence of TB is due to two major problems: the AIDS epidemic, which started in the mid-1980's, and the outbreak of multi-drug resistant (MDR) TB (Bezerra et al., 2006;Chung & Shin 2007;Naz et al., 2006). In connection with on-going studies designed to generate novel therapeutic anti-malarial agents, we recently described a new class of isonicotinic and benzoic acid N'-(3-phenylacryloyl)hydrazide derivatives as attractive anti-tubercular agents (Carvalho et al., 2008). Allied with these investigations are structural studies: the structure of N'-[(2E)-3-phenylprop-2-enoyl]benzohydrazide was recently reported by us (Carvalho et al., 2009). We have synthesized for biological study a series of PhCH═CHCONHN═CHC 6 H 4 X compounds and now we report the crystal and molecular structure of one of these (1: X = Cl).
The asymmetric unit of (I) comprises the hydrazide molecule and a water molecule of crystallization. Despite there being twists in the molecule of (I), Fig. 1

Refinement
The C-bound H atoms were geometrically placed (C-H = 0.95 Å) and refined as riding with U iso (H) = 1.2U eq (C). The Oand N-bound H atoms were located from a difference map and refined with the distance restraint O-H = 0.84 ± 0.01 and N-H = 0.86±0.01 Å, and with U iso (H) = zU eq (carrier atom); z = 1.5 for O and z = 1.2 for N. Fig. 1. The molecular structure of (I) showing displacement ellipsoids at the 50% probability level.  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 > 2σ(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.

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å 2 )
x y z U iso */U eq Cl 0.02800 (