Mechanism of the Participation of Water in the Decomposition of Hydrogen Trioxide (HOOOH). A Theoretical Study

Ab initio calculations at the MP4//MP2/6-31++G* level of
theory have shown a substantial reduction
(by 33.5 kcal/mol) of the energy barrier for the intramolecular
1,3-proton transfer in HOOOH to give water and
singlet oxygen (Δ1O2), when a molecule of
water, acting as a bifunctional catalyst, was allowed to participate in
the
process. The energy barriers, ΔE⧧ =
15.1 and 26.0 kcal/mol, relative to isolated reactants and
HOOOH−HOH
complex, respectively, were calculated. The following gas-phase
acidity order was found:  HOOOH (352 kcal/mol)
> HOOH (376 kcal/mol) > HOH (391 kcal/mol). HOOO-
was calculated to possess an exceptionally long HO−OO- bond (1.96 Å), indicating dissociation into
HO- and O2. It is most likely that this
species does not exist as a
distinguished molecular entity in water solutions of
HOOOH.