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

The potential energy profile for the F + (H2O)(3)-> HF + (H2O)(2)OH 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 center dot center dot center dot(H2O)(3) for all four reaction pathways are found lying ca. 7 kcal mol(-1) below the separated reactants F + (H2O)(3). The four reaction barriers on their respective reaction coordinates lie ca. 4 kcal mol(-1) below the reactants. There are also corresponding exit complexes HF center dot center dot center dot(H2O)(2)OH, lying about 13 kcal mol(-1) below the separated products HF + (H2O)(2)OH. Compared with analogous F + (H2O)(2) and F + H2O reactions, the F + (H2O)(3) reaction 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)(3) reaction.