Localized molecular-orbital representation of the bonding in N-sulphinosulphimides

Abstract

Localized molecular orbitals for the simplest N-sulphinosulphimide, H₂SNSO₂H, and of its conjugated acid have been calculated using the semiempirical CNDO/2 method. To understand the special features of the different bonds, a comparison is made with simpler molecules such as H₂S, Me₂SNH, Me₂SO, and Me₂SO₂. A three-centre S^IVNS^VIπ bond is formed in N-sulphinosulphimides which is localized mainly on the nitrogen atom. The S^IVN and S^VIN σ bonds as well as the nitrogen lone pair are considerably delocalized on to the neighbouring sulphur atoms. In all cases, the sulphur d-orbital participation in bonding is important. In Me₂SNH, Me₂SO, and Me₂SO₂, hyperconjugation of the CH bonds with the sulphur d orbitals occurs.