Intramolecular hydrogen-bonding effects on O-H stretch overtone excitation for fluorinated hydroperoxides

Applying computational methods for predicting gas-phase O-H stretch overtone spectra to the series of fluorinated hydroperoxides CF3OOH, CHF2OOH, and CH2FOOH reveals how intramolecular hydrogen bonding changes their overtone photochemistry, relative to their un-fluorinated analog CH3OOH. Intramolecular hydrogen bonding between fluorine and the hydroxyl hydrogen atom decreases O-H stretch frequencies and raises the barrier for torsion about the O-O bond. Whereas O-O torsion accompanies O-H stretch overtone excitation for CH3OOH, this is not the case for the fluorinated analogs that have intramolecular hydrogen bonding. The comparison highlights the molecular features that contribute to the feasibility of atmospheric overtone-induced O-O bond dissociation for CH3OOH, but not for its fluorinated analogs. (C) 2017 Published by Elsevier B.V.