Crystal structures of the sulfones of 2,3-diphenyl2,3-dihydro-4H-1,3-benzothiazin-4-one and 2,3diphenyl-2,3-dihydro-4H-pyrido[3,2-e][1,3]thiazin- 4-one

The title sulfones, 2,3-diphenyl-2,3-dihydro-4H-1,3-benzothiazine-1,1,4-trione, C20H15NO3S, and 2,3-diphenyl-2,3-dihydro-4H-pyrido[3,2-e][1,3]thiazine-1,1,4trione, C19H14N2O3S, crystallize in space group P21/n with two molecules in each of the asymmetric units and have almost identical unit cells and extended structures. In both structures, the thiazine rings exhibit a screw-boat pucker. The intermolecular interactions observed are C-H center dot center dot center dot O-type hydrogen bonds and parallel partial pi-pi stacking between the fused aromatic rings (benzo- or pyrido-) of the core of the molecules within each asymmetric unit, and also connecting to molecules with translational periodicity in the a-axis direction in what can be described as columns (two per asymmetric unit) of stacked molecules with alternating chirality. The pendant phenyl groups of both molecules do not participate in aromatic ring interactions.