Hydrogen-bond energies of FHF– and HOHF–. Ab initio studies of strong hydrogen bonds involving fluoride, using improved fluoride energies
Abstract
Using a large flexible Gaussian basis set the calculated hydrogen-bond energy of FHF– is 169 kJ mol–1, which agrees well with a recent gas-phase ion cyclotron resonance determination of 163 kJ mol–1. Reoptimization of the 4-31G and double-zeta basis-set scale factors for F results in substantially lower energies for the fluoride ion and also leads to much improved hydrogen-bond energies for FHF–. A similar improvement is found for HOHF–. The hydrogen-bond energy of the CH3OHF– complex is computed for the first time and shows good agreement with experiment. Other heteronuclear systems involving hydrogen bonding to F– have been recalculated using this approach.