4-Benzyl-6-p-tolyl­pyridazin-3(2H)-one

The title compound, C(18)H(16)N(2)O, is a new dihydro­pyridazin-3(2H)-one derivative synthesized in one step by condensation of α-benzyl­idene-γ-tolyl­butenolide with hydrazine. The mol­ecule is not planar; the tolyl and pyridazine rings are twisted with respect to each other making a dihedral angle of 27.35 (9)° and the benzyl ring is nearly perpendicular to the pyridazine ring with a dihedral angle of 85.24 (5)°. In the crystal structure, inversion dimers arise, being linked by pairs of N—H⋯O hydrogen bonds. Weak C—H⋯O hydrogen bonds and weak offset π–π stacking stabilize the packing. The π–π stacking occurs between the pyridazine rings of symmetry-related mol­ecules, with a centroid–centroid distance of 3.748 Å, an inter­planar distance of 3.605 Å and a slippage of 1.024 Å.