Crystal structure of (Z)-N′-[1-(3-methyl-5-oxo-1-phenyl-1,5-dihydro-4H-pyrazol-4-ylidene)propyl]benzenesulfonohydrazide

The title compound crystallizes in the keto form and the carbonyl O atom forms an intramolecular N—H⋯O hydrogen bond with the neighbouring NH group. In the crystal, molecules are linked by pairs of N—H⋯O hydrogen bonds to form inversion dimers, which are linked via pairs of C—H⋯O hydrogen bonds, forming chains propagating along [100].

The title compound, C 19 H 20 N 4 O 3 S, was synthesized by refluxing equimolar amounts of 1-phenyl-3-methyl-4-propionylpyrazol-5-one and benzenesulfonyl hydrazide in ethanol. The compound crystallizes in the keto form and the carbonyl O atom forms an intramolecular N-HÁ Á ÁO hydrogen bond with the neighbouring NH group. There is also C-HÁ Á ÁO short contact involving the neighbouring phenyl ring. Probably as a result of this, the phenyl ring is inclined to the pyrazolone ring by only 7.58 (12) . The dihedral angle between the phenyl ring and the benzenesulfonyl ring is 22.78 (11) . In the crystal, molecules are linked by pairs of N-HÁ Á ÁO hydrogen bonds, forming inversion dimers with an R 2 2 (14) ring motif. The dimers are linked via pairs of C-HÁ Á ÁO hydrogen bonds, forming chains propagating along [100].
In recent years, we have devoted our efforts to the design and synthesis of 4-acyl pyrazolone derivatives and their transition metal complexes (Zhang et al., 2004;Xu et al., 2013;Yi et al., 2014;Li et al., 2013). Such 4-acyl pyrazolone derivatives can form different types of complexes due to the multiple coordination sites and the tautomeric enol-to-keto effect. Furthermore, some of complexes have been shown to have strong antibacterial activity. For example, the copper complex

Structural commentary
The molecular structure of the title compound is shown in Fig. 1. The bond lengths and angles are close to the expected values. For example, the C7-O1 bond length of 1.259 (2) Å is in good agreement with that for a C=O double bond. The C9-N2 bond length of 1.298 (3) Å is consistent with that for a normal C=N double bond, which indicates that the compound exists in the keto form. In addition, the C11-N3 bond length of 1.335 (2) Å , is very close to that for a C-N single bond. The C8-C11 bond [1.387 (3) Å ] approaches the normal C=C bond length. These results indicate that the compound does not adopt the structure of a Schiff base.

Figure 1
The molecular structure of the title compound, with the atom labelling. Displacement ellipsoids are drawn at the 30% probability level.

Figure 2
A view of the crystal packing of the title compound, with the hydrogen bonds shown as dashed lines (see Table 1 for details).

Supramolecular features
In the crystal, atom N4 acts as a donor and forms an N-HÁ Á ÁO hydrogen bond with atom O1 i (Table 1). Molecules are linked by pairs of these hydrogen bonds, forming inversion dimers with an R 2 2 (14) ring motif. Neighbouring dimers are linked by pairs of C-HÁ Á ÁO hydrogen bonds, forming chains propagating along [100] (Table 1 and Fig. 2).

Synthesis and crystallization
1-Phenyl-3-methyl-4-propionyl-pyrazolone-5 (20 mmol, 4.6 g) was dissolved in 25 mL of hot anhydrous ethanol, and an ethanol solution of benzenesulfonyl hydrazide (20 mmol, 3.4 g) was slowly added with constant stirring. After adding a few drops of glacial acetic acid as catalyst, the mixture was refluxed for 4 h. After cooling, the precipitate that had formed was collected by filtration. A light-yellow product was obtained (yield 87%; m.p.: 483-484 K). Yellow block-like crystals, suitable for X-ray diffraction analysis, were obtained from a methanol solution upon slow evaporation at room temperature.

Refinement
Crystal data, data collection and structure refinement details are summarized in Table 2. The NH H atoms were located in a difference Fourier map and refined as riding atoms. C-bound H atoms were positioned geometrically and refined as riding: C-H = 0.93-0.97 Å with U iso (H) = 1.5U eq (C) for methyl H atoms and 1.2U eq (N,C) for other H atoms.  1-(3-methyl-5-oxo-1-phenyl-1,5-dihydro-4H-

Computing details
Data collection: RAPID-AUTO (Rigaku, 2004); cell refinement: RAPID-AUTO (Rigaku, 2004); data reduction: RAPID-AUTO (Rigaku, 2004); 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 (Sheldrick, 2008) and PLATON (Spek, 2009). 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 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.