(E)-4-Hydroxy-N′-(3,4,5-trimethoxybenzylidene)benzohydrazide

The title benzohydrazide derivative, C17H18N2O5, exists in a trans conformation with respect to the C=N double bond. The dihedral angle between the benzene rings is 19.41 (5)°. The two methoxy groups at the meta positions of the trimethoxybenzene group are almost coplanar with the ring [C—O—C—C = 1.62 (16) and 178.33 (10)°], whereas the third methoxy group, at the para position, is (+)-synclinal with the ring. In the crystal, molecules are linked by N—H⋯O and bifurcated O—H⋯(N,O) hydrogen bonds, as well as weak C—H⋯O interactions, into sheets lying parallel to the ac plane. A C—H⋯π interaction also occurs.

The title benzohydrazide derivative, C 17 H 18 N 2 O 5 , exists in a trans conformation with respect to the C N double bond. The dihedral angle between the benzene rings is 19.41 (5) . The two methoxy groups at the meta positions of the trimethoxybenzene group are almost coplanar with the ring [C-O-C-C = 1.62 (16) and 178.33 (10) ], whereas the third methoxy group, at the para position, is (+)-synclinal with the ring. In the crystal, molecules are linked by N-HÁ Á ÁO and bifurcated O-HÁ Á Á(N,O) hydrogen bonds, as well as weak C-HÁ Á ÁO interactions, into sheets lying parallel to the ac plane. A C-HÁ Á Á interaction also occurs.
In the crystal packing ( Fig. 2), the molecules are linked by N-H···O, O-H···N and O-H···O hydrogen bonds as well as with weak C-H···O interactions (Table 1) (Table 1).

Experimental
The title compound (I) was prepared by dissolving 4-hydroxybenzohydrazide (0.1 mmol, 0.15 g) in ethanol (15 ml) and a solution of 3,4,5-trimethoxybenzaldehyde (0.1 mmol, 0.19 g) in ethanol (15 ml) was then added to it0. The mixture was refluxed for around 3 hr and the white solid of the product that appeared was collected by filtration, washed with ethanol and dried in air. Colorless blocks of (I) were obtained after recrystalization from methanol by slow evaporation of the solvent at room temperature after several days, Mp. 532-533 K.

Refinement
Amide and hydroxy H atoms were located from the difference maps and refined isotropically. The remaining H atoms were positioned geometrically and allowed to ride on their parent atoms, with d(C-H) = 0.93 Å for aromatic and CH and 0.96 Å for CH 3 atoms. The U iso values were constrained to be 1.5U eq of the carrier atom for methyl H atoms and 1.2U eq for the remaining H atoms. A rotating group model was used for the methyl groups. Fig. 1. The molecular structure of the title compound, showing 50% probability displacement ellipsoids.

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.

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å 2 )
x y z U iso */U eq O1 0.02505 (5