Electronic Structure of Sulfimides: A Theoretical Study

Abstract

The electronic structure of sulfimides has been studied using the model system HN=SH2, 1, by performing ab initio calculations. There are two minima on the path of rotation across the S–N bond in 1. G2 calculations showed that the S–N rotational barrier in 1 is 8.50 kcal/mol. The inversion around S in 1 goes through a high-energy barrier of 26.85 kcal/mol at the same level. Substituent effects on the electronic structure were studied using Me, Cl, and F as substituents. Charge analysis using the NPA method has been performed to understand the electronic factors responsible for the observed trends in the S–N interactions. The NBO method was employed to quantitatively estimate the second-order interactions, which indicate that the S–N partial double-bond character in sulfimides is mainly attributable to negative hyperconjugative interactions, rather than pπ–pπ interactions.