Quantitative Dynamics of the Paradigmatic SN2 reaction OH− + CH3F on a Chemically Accurate Full-Dimensional Potential Energy Surface

25 August 2022, Version 2
This content is a preprint and has not undergone peer review at the time of posting.

Abstract

The bimolecular reaction between OH− and CH3F is not just a prototypical SN2 process but also has three other product channels. Here, we develop an accurate full-dimensional potential energy surface (PES) based on 191 193 points calculated at the level CCSD(T)-F12a/aug-cc-pVTZ. A detailed dynamics and mechanism analysis were carried out on this PES by using the quasi-classical trajectory approach. It is verified that the trajectories do not follow the minimum energy path (MEP) but directly dissociate to F− and CH3OH. In addition, a new transition state for proton exchange and a new product complex CH2F−‧‧‧H2O for proton abstraction were discovered. The trajectories avoid the transition state or this complex, instead dissociate to H2O and CH2F− directly through the ridge regions of the MEP before the transition state. These non-MEP dynamics become more pronounced at high collision energies. Detailed dynamics simulations provide new insights into the atomic-level mechanisms of the title reaction thanks to the new chemically accurate PES with the aid of the machine learning.

Keywords

SN2 reaction
non-IRC route
dynamic effect
full-dimensional accurate potential energy surface

Comments

Comments are not moderated before they are posted, but they can be removed by the site moderators if they are found to be in contravention of our Commenting Policy [opens in a new tab] - please read this policy before you post. Comments should be used for scholarly discussion of the content in question. You can find more information about how to use the commenting feature here [opens in a new tab] .
This site is protected by reCAPTCHA and the Google Privacy Policy [opens in a new tab] and Terms of Service [opens in a new tab] apply.