Observation of the nucleophilic displacement (SN2) reaction F- + CH3Br → CH3F + Br- induced by dissociative electron capture in binary van der Waals Clusters

We report on the S N 2 reaction F - + CH 3 Br→FCH 3 +Br - in binary clusters composed of CH 3 Br and C 2 F 6 in a crossed electron/molecular beam experiment. The reaction is induced by resonance dissociative electron attachment to the C 2 F 6 component where the nucleophile F - is generated at an energy (around 3.8 eV) where CH 3 Br does not capture electrons to form Br - . The results indicate that the cross section for the S N 2 reaction is independent of the total excess energy which can be varied between 1.7 and 5 eV in the present system.