4-(5-Oxo-3-phenyl-4,5-dihydro-1<i>H</i>-pyrazol-1-yl)benzenesulfonamide

With respect to the aliphatic planar five-membered ring (r.m.s. deviation = 0.011 Å) of the title compound, C(15)H(13)N(3)O(2)S, the phenyl ring is aligned at 6.9 (1)° and the phenyl-ene ring at 2.4 (1)°, so that the three rings are nearly coplanar. The amino group has the N atom in a pyramidal geometry; the group is a hydrogen-bond donor to the sulfonyl O atom of one mol-ecule and to the ketonic O atom of another mol-ecule, resulting in the formation of a layer parallel to the bc plane.