1-(5-Hydroxy-3-methyl-1-phenyl-1H-pyrazol-4-yl)ethanone: a new monoclinic polymorph

Abstract

The title compound, C12H12N2O2, crystallized in the monolinic space group P21/n, with two independent molecules (A and B) in the asymmetric unit. This is in contrast to the first monoclinic polymorph reported [Cingolani et al. (2002). Inorg. Chem. 41, 1151–116], which crystallized in the space group C2/c with one independent molecule per asymmetric unit. The dihedral angles between the two rings differ slightly; in molecule A it is 4.90 (11)° and in molecule B it is 16.05 (13)°. In both molecules, there is an intramolecular O—H...O hydrogen bond involving the hydroxyl substituent and the carbonyl O atom of the adjacent acetyl group. In the crystal structure, molecules A and B are linked via a C—H...N interaction. There are also some weak C—H...π interactions involving the phenyl ring of molecule A and H atoms of the acetyl groups of both molecules.