N′-[(E)-5-Bromo-2-hydroxy-3-methoxybenzylidene]-4-methoxybenzohydrazide monohydrate

In the title compound, C16H15BrN2O4·H2O, the hydrazide molecule is nearly planar, with a largest deviation from the mean plane through the non-H atoms of 0.106 (4) Å and a dihedral angle between the benzene rings of 1.98 (16)°. This molecule adopts an E conformation about the C=N bond and an intramolecular O—H⋯N hydrogen bond increases the rigidity. In the crystal, some molecules of the title hydrazide are replaced by molecules of its 6-bromo isomer, and the Br atom from this admixture molecule was refined to give a partial occupancy of 0.0523 (13). The hydrazide and water molecules are linked through classical N—H⋯O and O—H⋯O hydrogen bonds, forming layers parallel to (110). C—H⋯π interactions are also present.

In the title compound, C 16 H 15 BrN 2 O 4 ÁH 2 O, the hydrazide molecule is nearly planar, with a largest deviation from the mean plane through the non-H atoms of 0.106 (4) Å and a dihedral angle between the benzene rings of 1. 98 (16) . This molecule adopts an E conformation about the C N bond and an intramolecular O-HÁ Á ÁN hydrogen bond increases the rigidity. In the crystal, some molecules of the title hydrazide are replaced by molecules of its 6-bromo isomer, and the Br atom from this admixture molecule was refined to give a partial occupancy of 0.0523 (13). The hydrazide and water molecules are linked through classical N-HÁ Á ÁO and O-HÁ Á ÁO hydrogen bonds, forming layers parallel to (110). C-HÁ Á Á interactions are also present.
derivatives (Tan, 2012;Hou & Bi, 2012;Shen et al., 2012), we report here the crystal structure of a new aroylhydrazone compound. The molecular structure of the title compound is shown in Fig. 1.
The molecule adopts an E conformation about the C7═N1 bond and exists in keto form with C8═O3 bond length of 1.216 (2) Å, which is very close to a normal C═O bond length 1.21 Å (Allen et al., 1987).
In the crystal, approximately 5% of molecules of the title hydrazide are replaced by molecules of its 6-bromo isomer, and the Br1B atom of this admixture molecule was included in the refinement. Since the molecule of 6-bromo isomer is likely nonplanar due to sterical tensions, it does not occupy exactly the same position as the molecule of 5-bromo isomer.
As a result, Br1B deviates by 0.58 (4) Å from the mean plane of C1-C6 benzene ring, and the distance C1-Br1B is 1.67 (5) Å, that is much smaller than the typical bond length C-Br. On this reason, geometric parameters involving Br1B are not included in the cif-file.
Parallel arrangement of molecules in crystal is shown in Fig. 2. Adjacent molecules are linked through classical N-H···O and O-H···O hydrogen bonds, and a C-H···π interaction between one of the methyl H atoms and the phenyl ring of the adjacent molecule is also observed (see Table 1, Fig. 3). Weak π···π interactions are also present with a shortest separation between benzene ring centroids of 4.973 (3) Å.

Experimental
The title compound was prepared by adapting a reported procedure (Emmanuel et al., 2011;Mangalam & Kurup, 2011) by refluxing a mixture of methanolic solutions of 4-methoxybenzhydrazide (0.1661 g, 1 mmol) and 5-bromo-3-methoxysalicylaldehyde (0.2309 g, 1 mmol) for 4 h. The formed crystals were collected, washed with few drops of methanol and dried over P 4 O 10 in vacuo. Single crystals of the title compound suitable for X-ray analysis were obtained by slow evaporation from its methanolic solution. They contains approximately 5% of the 6-bromo isomer of the title compound.

Refinement
Bromine atoms Br1A and Br1B were refined freely, with the sum of their occupancy factors constrained to 1.0. All H atoms on C except of H1A and H1B were placed in calculated positions, with C-H bond distances 0.93-0.97 Å and U iso =1.2Ueq (1.5 for CH 3 ). The H1A atom was refined with restrained distance C1-H1A using DFIX instruction and with occupancy factor equal to that of Br1A. The H1B was placed in calculated position with occupancy factor equal to that of Br1B, and its coordinates were fixed. Hydrogen atoms attached to O and N atoms were located from difference maps, and the (N,O)-H distances were restrained using DFIX instructions. program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: ORTEP-3 (Farrugia, 1997) and DIAMOND (Brandenburg, 2010); software used to prepare material for publication: SHELXL97 (Sheldrick, 2008) and publCIF (Westrip, 2010).

Figure 1
The    Special details Geometry. All s.u.'s (except the s.u. in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell s.u.'s are taken into account individually in the estimation of s.u.'s in distances, angles and torsion angles; correlations between s.u.'s in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell s.u.'s is used for estimating s.u.'s 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 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.