Some doubly-charged cations can be stabilized in gas phase and their reactivity investigated by both theory and experiments. They can dissociate following two different processes that are in competition: a charge separation process referred to as ''Coulomb explosion'', leading to two monocations, and neutral loss fragmentation, where a new doubly-charged species, of lower mass, and a neutral molecule are obtained.We have employed theoretical approaches at different time-scale levels in order to have an almost complete picture and thus understand collision induced dissociation experiments for [Ca(urea)]2+ species.  QM+MM direct chemical dynamics was used to get rovibrational energy transfer after collision with inert atom (Ar) and reactivity in the pico-second time regime. These lasts provided both framentations and details on each pathway : neutral loss occurs mainly via a shattering mechanism, while Coulomb explosion follows statistical (or almost statistical) dynamics.Thus, RRKM rate constants were used in conjunction with obtained rovibration energy transfer probability distribution to elucidate the fragment formation as a function of time assuming complete IVR and statistical dynamics.We then show how dynamics can allow multiple reaction pathways thus leading to different products, even those not expected by a mere analysis of the potential energy surface.        References: 1)  I. Corral, O. Mo, M. Yanez, J.-Y. Salpin, J. Tortajada and L. Radom, J. Phys. Chem. A, 108, 10080�10088 (2004)2)  R.Spezia, A.Cimas, M.-P.Gaigeot, J.-Y.Salpin, K.Song and W.L.Hase. Phys. Chem. Chem. Phys., 14, 11724 - 11736 (2012).

Reactivity of doubly charged cations in the gas phase: Insights from chemical dynamics and statistical analysis

245th National Meeting (2013)

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