The title compound, C16H18N2O3, is constructed about a central oxopyridazinyl ring (r.m.s. deviation = 0.0047 Å), which is connected to an ethyl-acetate group at the N atom closest to the carbonyl group, and benzyl and methyl groups second furthest and furthest from the carbonyl group, respectively. An approximately orthogonal relationship exists between the oxopyridazinyl ring and the best plane through the ethyl-acetate group [dihedral angle = 77.48 (3)°]; the latter lies to one side of the central plane [the Nr-Nr-Cm-Cc (r = ring, m = methyl-ene, c = carbon-yl) torsion angle being 104.34 (9)°]. In the crystal, both H atoms of the N-bound methyl-ene group form methyl-ene-C-H⋯O(ring carbon-yl) or N(pyridazin-yl) inter-actions, resulting in the formation of a supra-molecular tape along the a-axis direction. The tapes are assembled into a three-dimensional architecture by methyl- and phenyl-C-H⋯O(ring carbon-yl) and phenyl-C-H⋯O(ester carbon-yl) inter-actions. The analysis of the calculated Hirshfeld surface indicates the dominance of H⋯H contacts to the overall surface (i.e. 52.2%). Reflecting other identified points of contact between mol-ecules noted above, O⋯H/H⋯O (23.3%), C⋯H/H⋯C (14.7%) and N⋯H/H⋯N (6.6%) contacts also make significant contributions to the surface.
Keywords: Hirshfeld surface analysis; crystal structure; ester; oxopyridazinyl.