| Attributs | Valeurs |
|---|
| type
| |
| Is Part Of
| |
| Subject
| |
| Title
| - Mechanistic Study of the CH3O2• + HO2• → CH3O2H + O2 Reaction in the Gas Phase.Computational Evidence for the Formation of a Hydrogen-Bonded Diradical Complex
|
| has manifestation of work
| |
| related by
| |
| Author
| |
| Abstract
| - In an attempt to understand the mechanism of the reaction of alkylperoxy radicals with hydroperoxy radical,a key reaction in both atmospheric and combustion chemistry, the singlet and triplet potential energy surfaces(PESs) for the gas-phase reaction between CH3O2• and HO2• leading to the formation of CH3OOH and O2have been investigated by means of quantum-mechanical electronic structure methods (CASSCF and CASPT2).In addition, standard transition state theory calculations have been carried out with the main purpose of aqualitative description of the strong negative temperature dependence observed for this reaction. All thepathways on both the singlet and triplet PESs consist of a reversible first step involving the barrierless formationof a hydrogen-bonded prereactive complex, followed by the irreversible formation of products. This complexis a diradical species where the two unpaired electrons are not used for bonding and is lying about 5 kcal/molbelow the energy of the reactants at 0 K. The lowest energy reaction pathway occurs on the triplet PES andinvolves the direct H-atom transfer from HO2 to CH3O2 in the diradical complex through a transition structurelying 3.8 kcal/mol below the energy of the reactants at 0 K. Contradicting the currently accepted interpretationof the reaction mechanism, the observed strong negative temperature dependence of the rate constant is dueto the formation of the hydrogen-bonded diradical complex rather than a short-lived tetraoxide intermediateCH3OOOOH.
|
| article type
| |
| is part of this journal
| |
