Crystal structure, Hirshfeld surface analysis and DFT study of (2Z)-2-(2,4-dichlorobenzylidene)-4-[2-(2-oxo-1,3-oxazolidin-3-yl)ethyl]-3,4-dihydro-2H-1,4-benzothiazin-3-one

The title compound, C20H16Cl2N2O3S, is built up from a di­hydro­benzo­thia­zine moiety linked by –CH– and –C2H4– units to 2,4-di­chloro­phenyl and 2-oxo-1,3-oxazolidine substituents, where the oxazole ring and the heterocyclic portion of the di­hydro­benzo­thia­zine unit adopt envelope and flattened-boat conformations, respectively. The 2-carbon link to the oxazole ring is nearly perpendicular to the mean plane of the di­hydro­benzo­thia­zine unit. In the crystal, the mol­ecules form stacks extending along the normal to (104) with the aromatic rings from neighbouring stacks inter­calating to form an overall layer structure. The Hirshfeld surface analysis of the crystal structure indicates that the most important contributions for the crystal packing are from H⋯H (28.4%), H⋯Cl/Cl⋯H (19.3%), H⋯O/O⋯H (17.0%), H⋯C/C⋯H (14.5%) and C⋯C (8.2%) inter­actions. Weak hydrogen-bonding and van der Waals inter­actions are the dominant inter­actions in the crystal packing. Density functional theory (DFT) optimized structures at the B3LYP/ 6–311 G(d,p) level are compared with the experimentally determined mol­ecular structure in the solid state. The HOMO—LUMO behaviour was elucidated to determine the energy gap.