Does the Cl + CH4 → H + CH3Cl Reaction Proceed via Walden Inversion?

László Krotos, G. Czakó

Research output: Contribution to journalArticle

4 Citations (Scopus)

Abstract

We report a chemically accurate global ab initio full-dimensional potential energy surface (PES) for the Cl(2P3/2) + CH4 reaction improving the high-energy region of our previous PES [Czakó, G.; Bowman, J. M. Science 2011, 334, 343-346]. Besides the abstraction (HCl + CH3) and the Walden-inversion substitution (H + CH3Cl) channels, the new PES accurately describes novel substitution pathways via retention of configuration. Quasiclassical trajectory simulation on this PES reveals that the substitution channel opens around 40 kcal/mol collision energy via Walden inversion and the retention cross sections raise from ∼50 kcal/mol. At collision energy of 80 kcal/mol, the retention pathways provide nearly 40% of the substitution cross section, and retention substitution may become the dominant mechanism of the Cl + CH4 reaction at superhigh collision energies. The substitution probability can be as high as ∼70% at zero impact parameter (b) and decreases rapidly with increasing b, whereas the abstraction opacity function is broad having 5-10% probability over a larger b-range. The high-energy angular distributions show scattering into forward and backward directions for the abstraction (direct stripping) and face-attack Walden-inversion substitution (direct rebound) channels, respectively. Retention can proceed via edge- and vertex-attack pathways producing dominant sideways scattering because the breaking C-H or Cl-H bond is usually at a side position of the forming Cl-C bond.

Original languageEnglish
Pages (from-to)9415-9420
Number of pages6
JournalJournal of Physical Chemistry A
Volume121
Issue number49
DOIs
Publication statusPublished - Dec 14 2017

ASJC Scopus subject areas

  • Physical and Theoretical Chemistry

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