3-Bromo-N′-(2-hydroxy-3,5-diiodobenzylidene)benzohydrazide monohydrate

Crystals of the title compound, C14H9BrI2N2O2·H2O, were obtained from a condensation reaction of 3-bromobenzohydrazide with 3,5-diiodosalicylaldehyde. The Schiff base molecule assumes an E configuration with respect to the C=N bond, and the dihedral angle between the two benzene rings is 6.9 (2)°. An intramolecular O—H⋯N hydrogen bond is observed in the Schiff base molecule and may contribute to its overall near planarity. In the crystal structure, molecules are linked through intermolecular O—H⋯O and N—H⋯O hydrogen bonds, forming layers parallel to the bc plane. Short intermolecular I⋯O contacts [2.930 (5) Å] are also found, linking the molecules into zigzag chains along b.

The asymmetric unit of (I) contains a Schiff base molecule and a water molecule of crystallization. The Schiff base molecule assumes an E configuration with respect to the C═N bond. The dihedral angle between the two benzene rings is 6.9 (2)°, indicating that the molecule is essentially planar. An intramolecular O-H···N hydrogen bond is observed in the Schiff base molecule and may contribute to its overall planarity. All bond lengths in (I) are within normal ranges (Allen et al., 1987) and comparable to the corresponding values in other similar compounds (Ejsmont et al., 2008;Narayana et al., 2007).
Experimental 3-Bromobenzohydrazide (1.0 mmol, 215.2 mg) and 3,5-diiodosalicylaldehyde (1.0 mmol, 374.9 mg) were stirred at room temperature for two hours. The filtrate was kept in air for a week to obtain yellow block-shaped crystals of (I).

Refinement
Atoms H2, H3A and H3B were located in a difference Fourier map and refined isotropically, with the N-H, O-H, and H···H distances restrained to 0.90 (1), 0.85 (1), and 1.37 (2) Å, respectively. Other H atoms were positioned geometrically and refined using a riding model with d(C-H) = 0.93 Å, d(O-H) = 0.82 Å and U iso = 1.2U eq (C) and 1.5U eq (O). Fig. 1. The molecular structure of (I), with 30% probability displacement ellipsoids. The intramolecular hydrogen bond is shown as a dashed line.

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.