Crystal structure of ( Z )-4-[1-(4-acetylanilino)ethylidene]-3-methyl-1-phenyl-1 H -pyrazol-5(4 H )-one

In the solid state, the title compound, C 20 H 19 N 3 O 2 , adopts the keto–amine tautomeric form, with the H atom attached to the N atom, which participates in an intramolecular N—H...O hydrogen bond with an S (6) ring motif. The dihedral angles between the pyrazole ring and the phenyl and benzene rings are 3.69 (10) and 46.47 (9)°, respectively. In the crystal, molecules are linked by weak C—H...O hydrogen bonds, generating C (16) chains propagating in [301]. Weak aromatic π–π stacking interactions [centroid–centroid distances = 3.6123 (10) and 3.6665 (10) Å] link the chains into a three-dimensional network.