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Dynamics and Novel Mechanisms of SN2 Reactions on ab Initio Analytical Potential Energy Surfaces
1Department of Physical Chemistry and Materials Science, Institute of Chemistry, University of Szeged , Rerrich Béla tér 1, Szeged H-6720, Hungary.
Abstract:
We describe a novel theoretical approach to the bimolecular nucleophilic substitution (SN2) reactions that is based on analytical potential energy surfaces (PESs) obtained by fitting a few tens of thousands high-level ab initio energy points. These PESs allow computing millions of quasi-classical trajectories thereby providing unprecedented statistical accuracy for SN2 reactions, as well as performing high-dimensional quantum dynamics computations. We developed full-dimensional ab initio PESs for the F- + CH3Y [Y = F, Cl, I] systems, which describe the direct and indirect, complex-forming Walden-inversion, the frontside attack, and the new double-inversion pathways as well as the proton-transfer channels. Reaction dynamics simulations on the new PESs revealed (a) a novel double-inversion SN2 mechanism, (b) frontside complex formation,
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