Reactivity of gaseous protonated ozone: a computational investigation on the carbon monoxide oxidation reaction

The gaseous protonated ozone has been experimentally observed in FT-ICR conditions to react with carbon monoxide promoting its oxidation to protonated carbon dioxide according to the reaction HO3+ + CO = OZ + HCO2+. This process, which in the past has been postulated to potentially represent a source of atmospheric ozone depletion, has been computationally addressed in this work. The singlet potential energy surface has been exhaustively investigated at the density functional theory and coupled cluster levels. The picture emerged from the quantum-chemical investigation describes such oxidation process as occurring essentially through a two-step mechanism in which the oxygen and hydrogen atoms are sequentially transferred from protonated ozone to carbon monoxide. By the use of standard statistical kinetics theories, the overall rate constants of the process has been also calculated in a temperature range between 50 and 500 K. Our computational work succeeds in reproducing both the 300 K overall rate constant and the nature of the products. (C) 2003 Elsevier Science B.V. All rights reserved.