crystal structure of (z)-n′-[1-(3-methyl-5-oxo-1-phenyl-1,5-dihydro-4h-pyrazol-4-ylidene)propyl]benzenesulfonohydrazide

The title compound, C19H20N4O3S, 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—H...O hydrogen bond with the neighbouring NH group. There is also C—H...O 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—H...O hydrogen bonds, forming inversion dimers with an R22(14) ring motif. The dimers are linked via pairs of C—H...O hydrogen bonds, forming chains propagating along [100].