Synthesis and structure of a 1:1 1-phenyl-semicarbazide-1-phenyl-pyrazolidin-3-one cocrystal.

The title cocrystal, C7H9N3O·C9H10N2O, was obtained by the cocrystallization of 1-phenyl-semicarbazide (A) and 1-phenyl-pyrazolidin-3-one (B) in a 1:1 molar ratio from methanol solution. The structure features a gauche arrangement about the N-N bond in the semicarbazide fragment and a twisted conformation of the pyrazolidinone ring. In the extended structure, the mol-ecules are linked by A → A and B → A N-H⋯O hydrogen bonds, supplemented by C-H⋯π contacts to generate a three-dimensional supra-molecular framework.