N′-[(Z)-4-Methylbenzylidene]-4-nitrobenzohydrazide monohydrate

In the title compound, C15H13N3O3·H2O, the two benzene rings form a dihedral angle of 2.03 (2)°. In the crystal structure, adjacent hydrazide molecules are linked into dimers by water molecules; these dimers are then stacked along the b axis. Intermolecular O—H⋯O, O—H⋯N and C—H⋯O hydrogen bonds and a π–π stacking interaction between the nitrobenzene and tolyl rings with a centroid–centroid distance of 3.8208 (3) Å are observed. There is also a short O⋯N contact [2.6824 (7) Å].

In the title compound, C 15 H 13 N 3 O 3 ÁH 2 O, the two benzene rings form a dihedral angle of 2.03 (2) . In the crystal structure, adjacent hydrazide molecules are linked into dimers by water molecules; these dimers are then stacked along the b axis. Intermolecular O-HÁ Á ÁO, O-HÁ Á ÁN and C-HÁ Á ÁO hydrogen bonds and astacking interaction between the nitrobenzene and tolyl rings with a centroid-centroid distance of 3.8208 (3) Å are observed. There is also a short OÁ Á ÁN contact [2.6824 (7) Å ].
Prompted by these review and in continuation of our work (Fun et al., 2008), we here in report the crystal structure of the title compound, (I).

Experimental
The title compound, C 15 H 15 N 3 O 4 , was obtained by refluxing 4-nitrobenzhydrazide (0.01 mol) and 4-methylbenzaldehyde (0.01 mol) in ethanol (30 ml) by adding 3 drops of concentrated sulfuric acid for 3 h. Excess ethanol was removed from the reaction mixture under reduced pressure. The solid product obtained was filtered, washed with water and dried. Crystals suitable for X-ray analysis were obtained from ethanol by slow evaporation.

Refinement
The amino and water H atoms were located in a difference map and refined with restraints of N-H = 0.85 (1) Å and O-H = 0.84 (1) Å. The remaining H atoms were positioned geometrically [C-H = 0.93 Å (aromatic) or 0.96 Å (methyl)] and refined using a riding model, with U iso (H) = 1.2U eq (aromatic C) and 1.5U eq (methyl C). A rotating group model was used for the methyl group.

Special details
Experimental. The data was collected with the Oxford Cyrosystem Cobra low-temperature attachment. 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.