Electronic structure of N-sulfonylimines

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)2NCH2 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 CN is more stable. NBO analysis has been carried out to quantitatively estimate these delocalisations and charge polarization in RS(O)2NCH2 (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 .