(4E)-4-[(2-Hy-droxy-anilino)methyl-idene]-1-phenyl-pyrazolidine-3,5-dione dimethyl sulfoxide hemisolvate.

The asymmetric unit of the title compound, C16H13N3O3·0.5C2H6OS, is composed of two independent pyrazolidine-3,5-dione mol-ecules and one dimethyl sulfoxide solvent mol-ecule. In each pyrazolidine-3,5-dione mol-ecule, an intra-molecular N-H⋯O hydrogen bond forms an S(5)S(6) motif. In the crystal, pairs of each independent pyrazolidine-3,5-dione mol-ecule are linked by N-H⋯O hydrogen bonds, forming dimers with R 2 (2)(8) motifs. These dimers are connected with the other mol-ecules through the solvent mol-ecules via O-H⋯O hydrogen bonds, forming ribbons along the b-axis direction. C-H⋯π inter-actions connect the ribbons. C-H⋯O interactions also occur.