Crystal structure of rac-2,3-diphenyl-2,3,5,6-tetrahydro-4H-1,3-thiazin-4-one 1-oxide

In the title compound, C16H15NO2S [alternative name: rac-2,3-diphenyl-1,3-thiazinan-4-one 1-oxide], the thiazine ring exhibits an envelope conformation, with the S atom forming the flap. The sulfoxide O atom is in a pseudo-axial position on the thiazine ring and is trans to the phenyl group on C-2. The phenyl rings form a dihedral angle of 89.47 (19)°. In this racemate crystal, homochiral molecules form slabs parallel to (010) of thickness b/2 which then stack with alternating chirality in the b-axis direction. The stacking is aided by edge-to-face interactions between the phenyl rings of racemic molecules. Within each of the single-enantiomer slabs, the molecules are held by C - H⋯O-type interactions, with an H⋯O distance of 2.30 Å, forming infinite chains along the c-axis direction, as well by the edge-to-face interactions between phenyl rings of neighboring molecules in the a-axis direction.