Theoretical studies on the S-N interactions in sulfoximine

The potential energy surface of sulfoximines has been searched using ab initio MO and Density Functional Calculations. The electronic structures of the isomers of sulfoximine have been studied using HF/6-31+G*, MP2(full)/6-31+G* and B3LYP/6-31+G* levels. Final energies of these molecules have been calculated at the high accuracy G2 and CBS-Q levels. Though a formal SN double bond is generally considered between sulfur and nitrogen in these systems, theoretical studies do not show any π interaction between them. S-N rotational barriers, bond dissociation energies, atomic charge analysis, and NBO analysis all indicate only a single bond across S-N with a very strong ionic interaction.