Unimolecular Reactions of Protonated Hydrogen Peroxide:  A Quantum Chemical Survey

The unimolecular chemistry of the system [HOOH]H + has been investigated using ab initio quantum chemical methods. In analogy with the isoelectronic systems [H 2 NNH 2 ]H + and [HONH 2 ]H +, in this paper subject to more detailed studies than previously the lowest energy pathway for decomposition of protonated hydrogen peroxide is loss of an oxygen atom in its triplet electronic state, giving H 3 O + as the ionic product. This process requires a crossover from the singlet to the triplet potential energy surface, and the minimum energy crossing point was located. The proton affinity was also calculated and found to be in good accordance with one experimental determination.