Electronic structure of N -sulfonylimines

Abstract

The electronic structure of N-sulfonylimines has been studied in detail using ab initio MO and density functional methods. The S–N rotational barriers in HS(O)2Ndouble bondCH2 at G2MP2 and CBS-Q levels have been found to be 3.25 and 3.43 kcal/mol respectively. Complete optimization at HF/6-31+G∗, MP2(full)/6-31+G∗ and B3LYP/6-31+G∗ levels have shown that synperiplanar arrangement of S–O with respect to Cdouble bondN is more stable. NBO analysis has been carried out to quantitatively estimate these delocalisations and charge polarization in RS(O)2Ndouble bondCH2 (R=H, Me, Cl, F). The Lewis basic character in N-sulfonylimines is less compared to N-alkylimines due to anomeric interactions that reduce the lone pair electron density on nitrogen in 1.