N′-(2-Hydroxy-3-methoxybenzylidene)-1,3-benzodioxole-5-carbohydrazide monohydrate

Single crystals of the title compound, C16H14N2O5·H2O, were obtained from a condensation reaction of 1,3-benzodioxole-5-carbohydrazide and 3-methoxysalicylaldehyde in a 95% ethanol solution. The asymmetric unit consists of a Schiff base molecule, which assumes an E configuration with respect to the C=N bond, and a water molecule of crystallization. The dihedral angle between the two substituted benzene rings is 12.7 (2)°. In the crystal structure, molecules are linked through intermolecular N—H⋯O and O—H⋯O hydrogen bonds, forming layers parallel to the bc plane.

The author acknowledges Liaodong University for research funding. properties (Okabe et al., 1993;Bedia et al., 2006;Rollas et al., 2002). Recently, a large number of hydrazone derivatives have been reported (Shan et al., 2008;Fun et al., 2008;Qu et al., 2008;Yehye et al., 2008). We report here the structure of a new hydrazone compound, I, Fig. 1, with a Schiff base molecule, which assumes an E configuration with respect to the C═N bond and a water molecule in the asymmetric unit. The dihedral angle between the two substituted benzene rings is 12.7 (2)°. All the bond lengths are within normal ranges (Allen et al., 1987).
In the crystal structure, molecules are linked through intermolecular N-H···O and O-H···O hydrogen bonds (Table 1), forming layers parallel to the bc direction ( Fig. 2).

Experimental
The title compound was prepared by Schiff base condensation reaction of 1,3-benzodioxole-5-carbohydrazide (1.0 mmol) and 3-methoxysalicylaldehyde (1.0 mmol) in a 95% ethanol solution (50 ml). Needle colorless crystals were formed by gradual evaporation of the solution in air for a few days.

Refinement
The imino H atom was located in a difference map and refined with a N-H distance restraint of 0.90 (1) Å. The water H atoms were also located in a difference map and refined with O-H and H···H distances restraints of 0.85 (1) and 1.37 (2) Å, respectively. The other H atoms were positioned geometrically [C-H = 0.93-0.97 Å] and refined using a riding model, with U iso (H) = 1.2U eq (C) and 1.5U eq (C methyl ). A rotating group model was used for the methyl group. In the absence of significant anomalous scattering effects, 1034 Friedel pairs were merged. Fig. 1. The structure of the title compound, showing 30% probability displacement ellipsoids and the atom-numbering scheme.

Special details
Geometry. All e.s.d.'s (except the e.s.d. in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell e.s.d.'s are taken into account individually in the estimation of e.s.d.'s in distances, angles and torsion angles; correlations between e.s.d.'s in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell e.s.d.'s is used for estimating e.s.d.'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 Rfactors(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.  (2) 168 (3)