Theoretical studies on the S-N interaction in sulfinamides

Abstract

The potential energy surface of sulfinamide H(O)S—NH2 (1) was searched, using ab initio and density functional methods, to study the conformational preferences. High‐accuracy G2MP2 calculations showed that the S—N rotational barrier in 1 is 7.0 kcal mol−1. The inversion around N in 1 goes through a very low energy barrier. Charge analysis using the NPA method was performed to elucidate the electronic factors responsible for the observed trends in the S—N interactions. The strength of negative hyperconjugation in 1 was estimated using NBO analysis and by studying the substituent effect. The repulsions between the lone pairs on oxygen and nitrogen and the nN → σ*S—O negative hyperconjugation play an important role in the conformations.