Theoretical study of nucleophilic substitution at two-coordinate sulfur

A series of nucleophilic substitution reactions involving simple species (chloride, phosphide, methoxide, hydroxide, and amide) as nucleophile and leaving group in methylsulfenyl derivatives were examined at B3LYP/aug-cc-pVDZ. The reactions involving hydroxide and amide correspond to deprotonation and not substitution. The substitution reactions follow an addition-elimination pathway, possessing a triple-well potential energy surface. The intermediate along this pathway is of trigonal bipyramid geometry with the nucleophile and leaving group occupying apical positions.