Density functional theory study on the reactions of X − with CH 3 SY (X, Y = F, Cl, Br, I)

Gas‐phase anionic reactions X − + CH 3 SY (X, Y = F, Cl, Br, I) have been investigated at the level of B3LYP/6‐311+G (2 df , p ). Results show that the potential energy surface (PES) of gas‐phase reactions X − + CH 3 SY (X, Y = Cl, Br, I) has a quadruple‐well structure, indicating an addition–elimination (A–E) pathway. The fluorine behaves differently in many respects from the other halogens and the reactions F − + CH 3 SY (Y = F, Cl, Br, I) correspond to deprotonation instead of substitution. The gas‐phase reactions X − + CH 3 SF (X = Cl, Br, I), however, follow an A–E pathway other than the last two out going steps (COM2 and PR) that proceeds via a deprotonation. The polarizable continuum model (PCM) has been used to evaluate the solvent effects on the energetics of the reactions X − + CH 3 SY (X, Y = Cl, Br, I). The PES is predicted to be unimodal in the solvents of high polarity. © 2007 Wiley Periodicals, Inc. Int J Quantum Chem, 2007