4-[(2,6-Dichlorophenyl)(hydroxyimino)-methyl]-1,5-dimethyl-2-phenyl-1,2-dihydropyrazol-3-one

The title compound, C18H15Cl2N3O2, was derived from the product of the intermolecular [3 + 2]-cycloaddition reaction of 2,6-dichlorobenzonitrile oxide and 1,5-dimethyl-2-phenyl-1,2-dihydropyrazol-3-one. The hydroxy group and the 2,6-dichlorophenyl ring of the oxime are in a trans conformation and the C==N-O angle is 113.90 (15) Angstrom. Pairs of molecules form centrosymmetric O-H ... N hydrogen-bonded dimers, with an O-H ... N distance of 2.821 (2) Angstrom. The pyrazole ring is nearly planar, with a mean deviation from the plane of 0.0246 (3) Angstrom and a dihedral angle between the pyrazole and the unsubstituted phenyl ring of 131.7 (4)degrees.