The crystal structure of 1-phenyl-3-methyl-4(salicylaldehyde hydrazone)-propenylidene-5-pyrazolone

The crystal structure of 1-phenyl-3-methyl-4-(salicylaldehyde hydrazone)-propenylidene-5-pyrazolone (PMPP-SH) was characterized by the single-crystal X-ray diffraction method. The cell parameters of PMPP-SH in the monoclinic P21/c space group are a = 10.851(1) Å, b = 11.679 (1) Å, c = 14.043 (2) Å and β = 91.89 (1)∘. Analyzing the molecular structure suggest that, in the solid state, the title compound exists mainly in enaminopyrazolone form, which is stabilized by intramolecular hydrogen bonding, rather than NH-form.