Crystal structure, Hirshfeld surface analysis and DFT study of 1-ethyl-3-phenyl-1,2-dihydroquinoxalin-2-one

In the title mol-ecule, C16H14N2O, the di-hydro-quinoxaline moiety is not planar as there is a dihedral angle of 4.51 (5)° between the constituent rings. In the crystal, C-H⋯O hydrogen bonds form helical chains about the crystallographic 21 screw axis in the b-axis direction. Hirshfeld surface analysis indicates that the most important contributions to the crystal packing are from H⋯H (51.7%), H⋯C/C⋯H (26%) and H⋯O/O⋯H (8.5%) inter-actions. The optimized structure calculated using density functional theory (DFT) at the B3LYP/6-311 G(d,p) level is compared with the experimentally determined structure in the solid state. The calculated HOMO-LUMO energy gap is 3.8918 eV.