Relationship between Strength of Hydrogen Bond and Barrier to Proton Transfer
Journal of Infectious Diseases
University of Chicago Press
Barriers to proton transfer are computed using ab initio methods for a number of systems, charged and uncharged, that contain either intramolecular or intermolecular H-bonds. It is shown that the very strong H-bonds that occur in ionic H-bonds between electronegative atoms like O or F are characterized by proton transfer potentials that have a single symmetric minimum. The transfer barrier that separates the two minima in less strongly-bound complexes rises as the H-bond weakens, as a result of involvement of less electronegative atoms. The weakening is evident from the equilibrium H-bond lengths, as well as the calculated energetics. The strain introduced into intramolecular H-bonds can act to raise the proton transfer barrier. Nonetheless, the relationship between weaker H-bonds and lower barriers is apparent, even in excited electronic states.
Relationship between Strength of Hydrogen Bond and Barrier to Proton Transfer S. Scheiner J. Mol. Struct., Theochem 1994 307, 65-71.