Dynamics and Novel Mechanisms of S(N)2 Reactions on ab lnitio Analytical Potential Energy Surfaces
We describe a novel theoretical approach to the bimolecular nucleophilic substitution (S(N)2) 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...
Elmentve itt :
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| Dokumentumtípus: | Cikk |
| Megjelent: |
2017
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| Sorozat: | JOURNAL OF PHYSICAL CHEMISTRY A
121 No. 47 |
| doi: | 10.1021/acs.jpca.7b08140 |
| mtmt: | 3313325 |
| Online Access: | http://publicatio.bibl.u-szeged.hu/17920 |
| Tartalmi kivonat: | We describe a novel theoretical approach to the bimolecular nucleophilic substitution (S(N)2) 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 S(N)2 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 S(N)2 mechanism, (b) frontside complex formation, (c) the dynamics of proton transfer, (d) vibrational and rotational mode specificity, (e) mode-specific product vibrational distributions, (f) agreement between classical and quantum dynamics, (g) good agreement with measured scattering angle and product internal energy distributions, and (h) significant leaving group effect in accord with experiments. |
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| Terjedelem/Fizikai jellemzők: | 9005-9019 |
| ISSN: | 1089-5639 |