Is there hydrogen bonding for gas phase SN2 pre-reaction complexes?

For some gas-phase X− + CH3Y → XCH3 + Y− SN2 nucleophilic substitution reactions a pre-reaction complex is formed in which the attacking anion binds to a H-atom to form X−⋯HCH2Y. In this work properties of this complex are investigated, for the OH− + CH3I and F− + CH3I reactions, to determine whether the HO−⋯HCH2I and F−⋯HCH2I complexes should be considered hydrogen-bonded complexes. Properties considered for these complexes are their structures, vibrational frequencies, well depths, and partial atomic charges. Also considered is the role of the HO−⋯HCH2I complex in proton transfer for both the proton transfer and SN2 reaction pathways. The results of these analyses indicate that these X−⋯HCH2Y complexes are hydrogen bonding complexes.