From Gas-Phase to Liquid-Water Chemical Reactions: The Fluorine Atom Plus Water Trimer System

Abstract

The potential energy profile for the F+(H2O)3→HF+(H2O)2OH reaction has been investigated using the “gold standard” CCSD(T) method with correlation-consistent basis sets up to cc-pVQZ. Four different reaction pathways have been found and these are related, both geometrically and energetically. The entrance complexes F⋅⋅⋅(H2O)3for all four reaction pathways are found lying ca. 7 kcal mol−1below the separated reactants F+(H2O)3. The four reaction barriers on their respective reaction coordinates lie ca. 4 kcal mol−1below the reactants. There are also corresponding exit complexes HF⋅⋅⋅(H2O)2OH, lying about 13 kcal mol−1below the separated products HF+(H2O)2OH. Compared with analogous F+(H2O)2and F+H2O reactions, the F+(H2O)3reaction is somewhat similar to the former but qualitatively different from the latter. It may be reasonable to predict that the reactions between atomic fluorine and water tetramer (or even larger water clusters) may be similar to the F+(H2O)3reaction.