Reaction Path Sampling of the Reaction between Iron(II) and Hydrogen Peroxide in Aqueous Solution

Abstract

Previously, we have studied the coordination and dissociation of hydrogen peroxide with iron(II) in aqueous solution by Car-Parrinello molecular dynamics at room temperature. We presented a few illustrative reaction events, in which the ferryl ion ([Fe(IV)O]2+) was formed either by a rebound mechanism or by a two-step mechanism via an iron(IV)dihydroxo intermediate, depending on the starting configuration, which was from either separated reactants or H2O2 already coordinated to the Fe2+ ion, respectively. In the present work, we test if the illustrative reaction events are indeed representative ones. This is done by generating two sequences of 10 reactive pathways each, using the transition path sampling technique, taking as the initial trajectory the previous reactive pathway which followed the rebound mechanism. Along the generated sequence of reaction pathways, we observed (a) decreasing lifetimes of the intermediate OH• radical, and (b) a change in the reaction mechanism toward the two-step mechanism ...