Crystal, molecular, and electronic structure of 2,5-diphenyl-1,4-dithiin 1-oxide

The crystal structure of 2,5-diphenyl-1,4-dithiin 1-oxide, C16H12O2S2, has been determined by a three-dimensional X-ray analysis. The crystals are orthorhombic, space group Pbca, with cell dimensions of a= 27·855, b= 12·162, and c= 8·089 A and Z= 8. The structure has been solved, by the symbolic-addition procedure, from 702 reflections collected by counter, and refined by least-squares methods to R 0·05.The heterocyclic ring is arranged in a boat structure with the sulphinyl oxygen in the axial position; the phenyl rings lie below the plane of the two CC bonds. The arrangement around the oxidized sulphur is slightly distorted pyramidal with the sulphur atom at the apex. The C–S bonds have different lengths: the two bonds to the unoxidized sulphur are significantly shorter than the C–S distance for the other two bonds to the sulphoxidic sulphur. This situation is discussed in terms of the CNDO method.