Theoretical studies on gas-phase reactions of negative ions with alkyl nitrites

Gas-Phase reactions of methyl and ethyl nitrites with anionic nucleophiles of SH-, F- and OH- are investigated theoretically at the MP2/6-311+G* level. The S(N)2 processes are all highly exothermic and proceed with a typical double-well reaction coordinate profile. The elimination reactions of methyl nitrite with SH- and F- are double-well energy surface processes, with stabilized product complexes of NO-... H2S and NO-... HF, proceeding by an Elcb-like E2 mechanism. The beta-elimination of ethyl nitrite is an E2 type process. The alpha-elimination reactions of methyl and ethyl nitrites with OH- have triple-well energy profiles of Elcb pathway with an alpha-carbanion intermediate which is stabilized by the vicinal n(C alpha)-sigma(O-N)* charge transfer interactions. Complexation of methyl carbanion with HF seems to provide a stable intermediate within a triple-well energy profile of Elcb channel in the reaction of F- with methyl nitrite.