THE $HF_{2}^{-}H_{2}O$ COMPLEX: A THEORETICAL STUDY
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Date
2000
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Publisher
Ohio State University
Abstract
In the gas phase, $HF^{-}_{2}$ is a hydrogen bonded species with a linear FHF geometry. The F-H distance is short and the hydrogen bond is strong. In the aqueous phase, it is known that the hydrogen bond in $HF^{-}_{2}$ is weakened due to hydrogen bonding between $HF^{-}_{2}$ and water molecules. We have examined the effect on the hydrogen bond in $HF^{-}_{2}$ due to hydrogen bonding between $HF^{-}_{2}$ and a single water molecule. For the $HF^{-}_{2} -H_{2} O$ complex we have calculated geometries and vibrational frequencies for the equilibrium structure and several transition state structures. We find that the equilibrium structure is a mere 0.2 kcal/mole below the transition state structures indicating that the complex is highly fluctional. We further find that whereas the F-H distance increase for the F atom hydrogen bonded to $H_{2}O$, the other F-H distance decreases. The F-F distance is essentially unchanged and the linearity of the FHF geometry is strictly maintained.
Description
Author Institution: Department of Chemistry, Wilfrid Laurier University