N′-(4-Hydroxy-3-methoxybenzylidene)acetohydrazide monohydrate

In the title compound, C10H12N2O3·H2O, the Schiff base molecule is approximately planar [within 0.189 (1) Å]. The interplanar angle between the benzene and acetohydrazide planes is 8.50 (10)°. In the crystal, molecules are linked into a three-dimensional network by strong and weak O—H⋯O and strong N—H⋯O hydrogen bonds. The hydroxy H atom deviates from the 4-hydroxy-3-methoxyphenyl mean plane by 0.319 (2) Å, probably due to the involvement of this H atom in the O—H⋯O hydrogen bond. The weak O—H⋯O hydrogen bond is involved in a bifurcated hydrogen bond with R 1 2(4) motif. A weak C—H⋯π interaction is also present.

In the title compound, C 10 H 12 N 2 O 3 ÁH 2 O, the Schiff base molecule is approximately planar [within 0.189 (1) Å ]. The interplanar angle between the benzene and acetohydrazide planes is 8.50 (10) . In the crystal, molecules are linked into a three-dimensional network by strong and weak O-HÁ Á ÁO and strong N-HÁ Á ÁO hydrogen bonds. The hydroxy H atom deviates from the 4-hydroxy-3-methoxyphenyl mean plane by 0.319 (2) Å , probably due to the involvement of this H atom in the O-HÁ Á ÁO hydrogen bond. The weak O-HÁ Á ÁO hydrogen bond is involved in a bifurcated hydrogen bond with R 1 2 (4) motif. A weak C-HÁ Á Á interaction is also present.

Experimental
Data collection: SMART (Bruker, 2002); cell refinement: SAINT (Bruker, 2002); 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: SHELXTL.  (Cimerman et al., 1997). They are also important ligands, which have been reported to show mild bacteriostatic activity and to be potential oral iron-chelating drugs for genetic disorders such as thalassemia (Offe et al., 1952;Richardson et al., 1988). Metal complexes based on Schiff bases have received considerable attention because they can be utilized as model compounds with active centres in various complexes (Tamboura et al., 2009). Here we report the crystal structure of the title compound ( Fig. 1).

Structure Reports Online
In the Schiff base molecule, the acetohydrazide group is planar and it contains a dihedral angle equal 8.50 (10)° to the benzene ring. The molecule adopts the trans configuration with respect to the C═N bond. Bond lengths and angles are comparable to those observed for N'-[1-(4-methoxyphenyl)ethylidene]acetohydrazide (Li et al., 2008).
In the crystal structure, the Schiff base and water molecules are linked into a three-dimensional network by strong and weak (Desiraju & Steiner, 1999) O-H···O and strong N-H···O hydrogen bonds (Tab. 1). The weak O-H···O hydrogen bond is involved in the bifurcated hydrogen bond with the motif R 2 1 (4) (Etter et al., 1990). Intermolecular C-H···π interactions are also present in the structure. It is of interest, that the atom H1 of the hydroxyl group deviates significantly from the mean plane of 4-hydroxy-3-methoxyphenyl (the atoms C1-C7//O1//O2) by 0.319 (2)Å. This feature can be explained by its involvement into the O1-H1···O1W hydrogen bond (Tab. 1).
Experimental 4-Hydroxy-3-methoxybenzaldehyde (1.50 g, 0.01 mol) and acetohydrazide (0.74 g, 0.01 mol) were dissolved in methanol (20 ml) and stirred for 1.5 h at room temperature. The resulting solid was filtered off and recrystallized from ethanol to give the title compound in 88% yield. Colourless single crystals (0.8 × 0.6 × 0.5mm) suitable for X-ray analysis were obtained by slow evaporation from ethanol solution at room temperature (m. p. 492-494 K).

Refinement
All the hydrogen atoms could have been discerned in the difference electron density map, nevertheless, all the hydrogens attached to the carbon atoms were constrained in a riding motion approximation: C aryl -H = 0.93, C methyl -H = 0.96Å; U iso H aryl = 1.2U eq C aryl , U iso H methyl =1.5U eq C methyl . The coordinates of the water hydrogens were freely refined with U iso H Ow =1.5U eq Ow. The N2-H2 distance was restrained to 0.87 (2) Å, U iso H2 =1.2U eq N2.
supplementary materials sup-2 Figures   Fig. 1. The asymmetric unit of the title structure. The displacement ellipsoids are drawn at the 40% probability level. The dashed lines indicate the hydrogen bonds.

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.