Crystal structure of (E)-N-{2-[2-(2-chlorobenzylidene)hydrazin-1-yl]-2-oxoethyl}-4-methylbenzamide monohydrate

The title compound is twisted in such a way that the almost planar [Car—C(=O)—N(H)—C(H2] and [C(H2)—C(=O)N(H)—N=C(H)—Car] segments are inclined to on another by 77.36 (8)°, while the benzene rings are inclined to one another by 89.69 (9)°. In the crystal, molecules are linked via pairs of N—H⋯O hydrogen bonds, forming inversion dimers which are linked by O—H⋯O hydrogen bonds, involving the crystal water molecule, forming chains propagating along the a-axis direction.

The title compound, C 17 H 16 ClN 3 O 2 ÁH 2 O, an acylhydrazone derivative, contains a glycine moiety and two substituted benzene rings on either end of the chain. It crystallized as a monohydrate. The molecules adopt an E conformation with respect to the C N double bond, as indicated by the N-N C-C torsion angle of 179.38 (14) . The molecule is twisted in such a way that the almost planar C ar -C( O)-N(H)-C(H 2 ) and C(H 2 )-C( O)N(H)-N C-C ar [r.m.s deviations = 0.009 and 0.025 Å , respectively] segments are inclined to on another by 77.36 (8) , while the benzene rings are normal to one another, making a dihedral angle of 89.69 (9) . In the crystal, the water molecule links three molecules through two O-HÁ Á ÁO and one N-HÁ Á ÁO hydrogen bonds. The molecules are linked via pairs of N-HÁ Á ÁO hydrogen bonds, forming inversion dimers with an R 2 2 (14) ring motif. The dimers are linked by O-HÁ Á ÁO hydrogen bonds, involving two molecules of water, forming chains along [100], enclosing R 2 2 (14) and R 2 2 (18) ring motifs. The chains are linked through C-HÁ Á ÁO interactions, forming sheets parallel to (010). Within the sheets, there are C-HÁ Á Á and parallel slippedstacking interactions present [inter-centroid distance = 3.6458 (12) Å ].

Chemical context
N-Acylhydrazones have been reported to be promising in terms of their future potential as antibacterial drugs (Osorio et al., 2012). These predictions have provided a therapeutic pathway to develop new effective biologically active Schiffbase derivatives. N-Acylhydrazones may exist as Z/E geometrical isomers about the C N double bond and as syn/anti amide conformers (Palla et al., 1986). The carbonyl group in the acylhydrazone provides the possibility for electron delocalization within the hydrazone moiety. The anti-TNFactivity of glycinyl-hydrazone derivatives indicate that differences in the hydrophobicity of the imine-attached framework plays an important role. The study of conformational isomers of the amide unit of an N-methyl N-acylhydrazone derivative suggested that the amino spacer does not participate as a hydrogen-bond donor in the stabilization of the conformational isomers in solution (Lacerda et al., 2012).

Figure 1
The molecular structure of the title compound, showing the atom labelling. Displacement ellipsoids are drawn at the 50% probability level.

Figure 2
Hydrogen-bonding pattern in the title compound (see Table 1 for details). [Symmetry codes: (a) Àx + 1, Ày + 1, Àz; hydrazide hydrogen atom and the other with one of the hydrogen atoms of the water molecule (O3). The two hydrogen atoms of the water molecule are involved in hydrogen bonding with the O atoms of the amide carbonyl (O3-H31Á Á ÁO1) and glycine carbonyl (O3-H32Á Á ÁO2) groups of two different molecules of the title compound. The O atom is also involved in hydrogen bonding with the H atom of the carbonylamide group of a third symmetry-related molecule (N1-H1NÁ Á ÁO3). A pair of N2-H2NÁ Á ÁO1 intermolecular hydrogen bonds link the molecules, forming inversion dimers, with an R 2 2 (14) ring motif. The dimers are further linked via hydrogen bonds involving the water molecule generating R 4 4 (14) and R 4 4 (18) ring motifs. Further, the N2-H2NÁ Á ÁO1 and N1-H1NÁ Á ÁO3 hydrogen bonds between the molecules of the main compound and water molecules translate into C 2 2 (6) chains along the a-axis direction (Table 1 and Fig. 2) The chains are linked by a C-HÁ Á ÁO interaction, forming sheets parallel to (010). Within the sheets there are C-HÁ Á Á, and parallel slippedstacking interactions [Cg2Á Á ÁCg2 i = 3.6458 (12) Å ; inter-planar distance = 3.4135 (8) Å , slippage = 1.281 Å ; Cg2 is the centroid of ring C11-C16; symmetry code: (i) Àx + 1, Ày + 1, Àz + 1] involving inversion-related chlorobenzene rings; see Fig. 3.

Database survey
A search of the Cambridge Structural Database (Version 5.36, May 2015; Groom & Allen, 2014) for the fragment -NH-CH 2 -C( O)-NH-N CH-, yielded only one hit, namely N-(2hydroxy-1-naphthylmethylene)-N 0 -(N-phenylglycyl)hydrazine (MEMTOO; Gudasi et al., 2006). A comparison of the structural details of the title compound, (I), with those of the recently published sulfonyl derivative, (E)-N-{2-[2-(3-chlorobenzylidene)hydrazinyl]-2-oxoethyl}-4-methylbenzenesulfonamide monohydrate (II) (Purandara et al., 2015), reveals the trans orientation of the amide group (C1-C7( O1)N1) and hydrazone segment (N2-N3 C10-C11) with respect to the glycinyl C8-C9 bond in (I), as is evident from the N1-C8-C9-N2 torsion angle of 173.58 (15) , in contrast to the cis orientation of the sulfonamide and hydrazone segments, with respect to the glycinyl C-C bond, observed in compound (II). In the structure of (I), the benzene ring (C1-C6) is almost coplanar with the amide group [dihedral angle = 8.21 (13) ]. This is in contrast to the L-shaped conformation (bent at the S atom) of the sulfonamide group with respect to the benzene ring in compound (II). The amide carbonyl O atom forms stronger O-HÁ Á ÁO hydrogen bonds with the water H atoms than the sulfonyl O atom as observed in compound (II), indicating the stronger electron-withdrawing character of the amide group compared to the sulfonamide group.

Synthesis and crystallization
Triethylamine (0.03 mol) and 4-methylbenzoyl chloride (0.01 mol) were added to a stirred suspension of glycine ethylester hydrochloride (0.01 mol) in dichloromethane (50 ml) in an ice bath. The reaction mixture was stirred at room temperature for 20 h. After completion of the reaction, 2N hydrochloric acid (80 ml) was added slowly. The organic phase was separated and washed with water (30 ml), dried with anhydrous Na 2 SO 4 and evaporated to yield the corresponding ester, N-(4-methylbenzoyl)glycine ethyl ester (L1). L1 (0.01 mol) was added in small portions to a stirred solution of 99% hydrazine hydrate (10 ml) in 30 ml ethanol. The mixture was refluxed for 6 h. After cooling to room temperature, the resulting precipitate was filtered, washed with cold water and dried to give N-(4-methylbenzoyl)glycinyl hydrazide (L2). 2-Chlorobenzaldehyde (0.01 mol) and two drops of glacial acetic acid were added to L2 (0.01 mol) in anhydrous methanol (30 ml). The reaction mixture was refluxed for 8 h. After cooling, the precipitate was collected by vacuum filtration, washed with cold methanol and dried. It was recrystallized to constant melting point from methanol (479-480 K). Prism-like colourless single crystals of the title compound were grown from a solution in DMF by slow evaporation of the solvent.
The purity of the compound was checked by TLC and characterized by its IR spectrum. A view along the a axis of the crystal packing of the title compound. Hydrogen bonds are shown as dashed lines and C-HÁ Á Á interactions are represented as red arrows (see Table 1 42.04, 126.60, 126.83, 127.28, 128.64, 129.66, 130.85, 131.35, 133.10, 139.45, 141.06, 142.70, 165.98, 166.54, 170.48.

Refinement
Crystal data, data collection and structure refinement details are summarized in Table 2. The water H atoms and the NH H atoms were located in a difference Fourier map and refined with distances restraints: O-H = 0.85 (2), N-H = 0.86 (2) Å with U iso (H) = 1.5U eq (O) and 1.2U eq (N). The C-bound H atoms were positioned with idealized geometry and refined as riding atoms: C-H = 0.93-0.97 Å with U iso (H) = 1.5U eq (C) for methyl H atoms and 1.2U eq (C) for other H atoms.