(E)-N′-(3,5-Dichloro-2-hydroxybenzylidene)-2-methoxybenzohydrazide

In the title compound, C15H12Cl2N2O3, the dihedral angle between the two substituted aromatic rings is 5.4 (4)°. Intramolecular O—H⋯N and N—H⋯O hydrogen bonds affect the planarity of the molcular conformation, with a mean deviation from the plane defined by the non-H atoms of 0.062 (2) Å. The molecule exists in a trans configuration with respect to the methylidene unit. In the crystal, molecules are linked by N—H⋯O interactions.

In the title compound, C 15 H 12 Cl 2 N 2 O 3 , the dihedral angle between the two substituted aromatic rings is 5.4 (4) . Intramolecular O-HÁ Á ÁN and N-HÁ Á ÁO hydrogen bonds affect the planarity of the molcular conformation, with a mean deviation from the plane defined by the non-H atoms of 0.062 (2) Å . The molecule exists in a trans configuration with respect to the methylidene unit. In the crystal, molecules are linked by N-HÁ Á ÁO interactions.  Data collection: SMART (Bruker, 1998); cell refinement: SAINT (Bruker, 1998); data reduction: SAINT; program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: SHELXTL (Sheldrick, 2008); software used to prepare material for publication: SHELXL97.
In the crystal structure of the title hydrazone molecule, as shown in Fig. 1, the dihedral angle between the two substituted aromatic rings is 5.4 (4)°. The intramolecular O-H···N and N-H···O hydrogen bonds (Table 1) affect the planarity of the conformation of the molecule. The molecule exists in a trans configuration with respect to the methylidene unit.

Experimental
A mixture of 2-methoxybenzhydrazide (0.166 g, 1 mmol) and 3,5-dichlorosalicylaldehyde (0.190 g, 1 mmol) in 30 ml of ethanol containing a few drops of acetic acid was refluxed for about 1 h. On cooling to room temperature, a solid precipitate was formed. The solid was filtered and then recrystallized from methanol. Colorless crystals suitable for X-ray diffraction were obtained by slow evaporation of the solution.

Refinement
The and N-bound hydrogen atom was located from a difference Fourier map and refined isotropically. The rest of hydrogen atoms were positioned geometrically [C-H = 0.93 & 0.96 Å; O-H = 0.82 Å] and refined using a riding model [U iso (H) = 1.2U eq (C) and 1.5 U eq (C15 and O1)]. A rotating-group model was applied for the methyl group. Fig. 1. The molecular structure with displacement parameters drawn at the 30% probability level. Hydrogen bonds are indicated by dashed lines.

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.