The Effect of Microsolvation on E2 and SN2 Reactions: Theoretical Study of the Model System F + C2H5F + nHF

Authors

  • Dr. F. Matthias Bickelhaupt,

    Corresponding author
    1. Sectie Theoretische Chemie, Scheikundig Laboratorium der Vrije Universiteit De Boelelaan 1083, NL-1081 HV Amsterdam (The Netherlands) Telefax: Int. code +(20)44-47643
    • Sectie Theoretische Chemie, Scheikundig Laboratorium der Vrije Universiteit De Boelelaan 1083, NL-1081 HV Amsterdam (The Netherlands) Telefax: Int. code +(20)44-47643
    Search for more papers by this author
  • Prof. Dr. Evert Jan Baerends,

    Corresponding author
    1. Sectie Theoretische Chemie, Scheikundig Laboratorium der Vrije Universiteit De Boelelaan 1083, NL-1081 HV Amsterdam (The Netherlands) Telefax: Int. code +(20)44-47643
    • Sectie Theoretische Chemie, Scheikundig Laboratorium der Vrije Universiteit De Boelelaan 1083, NL-1081 HV Amsterdam (The Netherlands) Telefax: Int. code +(20)44-47643
    Search for more papers by this author
  • Prof. Dr. Nico M. M. Anibbering

    1. Instituut voor Massaspectrometrie, Universiteit van Amsterdam Nieuwe Achtergracht 129, NL-1018 WS Amsterdam (The Netherlands) Fax: Int. code +(20)525-6971
    Search for more papers by this author

Abstract

The model reaction system F +C2H5F + nHF (n = 0–4) has been investigated by use of a density-functional method, in order to achieve a qualitative understanding of the effect of solvation on the E2 and SN2 reactions. Two characteristic effects already occur upon monosolvation: a) the activation energies of the E2 and SN2 pathways increase significantly and even become positive, because reactants are more strongly solvated than transition states; b) the SN2 transition state is stabilized much more and becomes lower in energy than the anti-E2 transition state. This agrees with general experience from gas- and condensed-phase experiments. The solvation is analyzed from two complementary viewpoints: a) as an interaction between solvent molecules and the F/C2H5F reaction system; b) as an interaction between the [F, nHF] solvated base and the C2H5F substrate. The extent to which condensed-phase characteristics can be modeled by this microsolvation approach is discussed.

Ancillary