Skip to main content

Thank you for visiting You are using a browser version with limited support for CSS. To obtain the best experience, we recommend you use a more up to date browser (or turn off compatibility mode in Internet Explorer). In the meantime, to ensure continued support, we are displaying the site without styles and JavaScript.

Atomistic dynamics of elimination and nucleophilic substitution disentangled for the F + CH3CH2Cl reaction


Chemical reaction dynamics are studied to monitor and understand the concerted motion of several atoms while they rearrange from reactants to products. When the number of atoms involved increases, the number of pathways, transition states and product channels also increases and rapidly presents a challenge to experiment and theory. Here we disentangle the dynamics of the competition between bimolecular nucleophilic substitution (SN2) and base-induced elimination (E2) in the polyatomic reaction F + CH3CH2Cl. We find quantitative agreement for the energy- and angle-differential reactive scattering cross-sections between ion-imaging experiments and quasi-classical trajectory simulations on a 21-dimensional potential energy hypersurface. The anti-E2 pathway is most important, but the SN2 pathway becomes more relevant as the collision energy is increased. In both cases the reaction is dominated by direct dynamics. Our study presents atomic-level dynamics of a major benchmark reaction in physical organic chemistry, thereby pushing the number of atoms for detailed reaction dynamics studies to a size that allows applications in many areas of complex chemical networks and environments.

Access options

Rent or Buy article

Get time limited or full article access on ReadCube.


All prices are NET prices.

Fig. 1: Reaction of F + CH3CH2Cl.
Fig. 2: Differential scattering cross-sections.
Fig. 3: Direct fractions and product branching ratios.
Fig. 4: Internal energy Eint distributions for the E2 reaction.

Data availability

Data are provided in the online material accompanying this article. Source data are provided with this paper.


  1. 1.

    Xie, Y. et al. Quantum interference in H + HD → H2 + D between direct abstraction and roaming insertion pathways. Science 368, 767–771 (2020).

    CAS  Article  Google Scholar 

  2. 2.

    Zhang, X., Li, L., Chen, J., Liu, S. & Zhang, D. H. Feshbach resonances in the F + H2O → HF + OH reaction. Nat. Commun. 11, 223 (2020).

    CAS  Article  Google Scholar 

  3. 3.

    Yang, T. et al. Enhanced reactivity of fluorine with para-hydrogen in cold interstellar clouds by resonance-induced quantum tunnelling. Nat. Chem. 11, 744–749 (2019).

    CAS  Article  Google Scholar 

  4. 4.

    Pan, H., Liu, K., Caracciolo, A. & Casavecchia, P. Crossed beam polyatomic reaction dynamics: recent advances and new insights. Chem. Soc. Rev. 46, 7517–7547 (2017).

    CAS  Article  Google Scholar 

  5. 5.

    Liu, K. Vibrational control of bimolecular reactions with methane by mode, bond, and stereo selectivity. Annu. Rev. Phys. Chem. 67, 91–111 (2016).

    CAS  Article  Google Scholar 

  6. 6.

    Brouard, M., Parker, D. H. & van de Meerakker, S. Y. T. Taming molecular collisions using electric and magnetic fields. Chem. Soc. Rev. 43, 7279–7294 (2014).

    CAS  Article  Google Scholar 

  7. 7.

    Zhao, Z. Q., Zhang, Z. J., Liu, S. & Zhang, D. H. Dynamical barrier and isotope effects in the simplest substitution reaction via Walden inversion mechanism. Nat. Commun. 8, 14506 (2017).

    Article  Google Scholar 

  8. 8.

    Estillore, A. D., Visger, L. M. & Suits, A. G. Imaging the dynamics of chlorine atom reactions with alkenes. J. Chem. Phys. 133, 074306 (2010).

    Article  Google Scholar 

  9. 9.

    Herman, Z. & Futrell, J. H. Dynamics of ion-molecule reactions from beam experiments: A historical survey. Int. J. Mass Spectrom. 377, 84–92 (2015).

    CAS  Article  Google Scholar 

  10. 10.

    Wang, Y. et al. Mode-specific SN2 reaction dynamics. J. Phys. Chem. Lett. 7, 3322–3327 (2016).

    CAS  Article  Google Scholar 

  11. 11.

    Carrascosa, E., Meyer, J. & Wester, R. Imaging the dynamics of ion–molecule reactions. Chem. Soc. Rev. 46, 7498–7516 (2017).

    CAS  Article  Google Scholar 

  12. 12.

    Xie, J. & Hase, W. L. Rethinking the SN2 reaction. Science 352, 32–33 (2016).

    CAS  Article  Google Scholar 

  13. 13.

    Gronert, S. Gas phase studies of the competition between substitution and elimination reactions. Acc. Chem. Res. 36, 848–857 (2003).

    CAS  Article  Google Scholar 

  14. 14.

    Villano, S. M., Kato, S. & Bierbaum, V. M. Deuterium kinetic isotope effects in gas-phase SN2 and E2 reactions: A comparison of experiment and theory. J. Am. Chem. Soc. 128, 736–737 (2006).

    CAS  Article  Google Scholar 

  15. 15.

    Tajti, V. & Czakó, G. Benchmark ab initio characterization of the complex potential energy surface of the F + CH3CH2Cl reaction. J. Phys. Chem. A 121, 2847–2854 (2017).

    CAS  Article  Google Scholar 

  16. 16.

    Yang, L. et al. Competing E2 and SN2 mechanisms for the F + CH3CH2I reaction. J. Phys. Chem. A 121, 1078–1085 (2017).

    CAS  Article  Google Scholar 

  17. 17.

    Carrascosa, E. et al. Imaging dynamic fingerprints of competing E2 and SN2 reactions. Nat. Commun. 8, 25 (2017).

    Article  Google Scholar 

  18. 18.

    Hamlin, T. A., Swart, M. & Bickelhaupt, F. M. Nucleophilic substitution (SN2): Dependence on nucleophile, leaving group, central atom, substituents, and solvent. ChemPhysChem 19, 1315–1330 (2018).

    CAS  Article  Google Scholar 

  19. 19.

    Eyet, N., Melko, J. J., Ard, S. G. & Viggiano, A. A. Effect of higher order solvation and temperature on SN2 and E2 reactivity. Int. J. Mass Spectrom. 378, 54–58 (2015).

    CAS  Article  Google Scholar 

  20. 20.

    Hase, W. L. Simulations of gas-phase chemical reactions: applications to SN2 nucleophilic substitution. Science 266, 998–1002 (1994).

    CAS  Article  Google Scholar 

  21. 21.

    Viggiano, A. A., Morris, R. A., Paschkewitz, J. S. & Paulson, J. F. Kinetics of the gas-phase reactions of chloride anion, Cl with CH3Br and CD3Br: experimental evidence for nonstatistical behavior? J. Am. Chem. Soc. 114, 10477–10482 (1992).

    CAS  Article  Google Scholar 

  22. 22.

    Sun, L., Song, K. & Hase, W. L. A SN2 reaction that avoids its deep potential energy minimum. Science 296, 875–878 (2002).

    CAS  Article  Google Scholar 

  23. 23.

    Czakó, G. et al. Benchmark ab initio and dynamical characterization of the stationary points of reactive atom + alkane and SN2 potential energy surfaces. Phys. Chem. Chem. Phys. 22, 4298–4312 (2020).

    Article  Google Scholar 

  24. 24.

    Xie, J. et al. Identification of atomic-level mechanisms for gas-phase X + CH3Y SN2 reactions by combined experiments and simulations. Acc. Chem. Res. 47, 2960–2969 (2014).

    CAS  Article  Google Scholar 

  25. 25.

    Meyer, J. et al. Unexpected indirect dynamics in base-induced elimination. J. Am. Chem. Soc. 141, 20300–20308 (2019).

    CAS  Article  Google Scholar 

  26. 26.

    Liu, X., Zhang, J., Yang, L. & Hase, W. L. How a solvent molecule affects competing elimination and substitution dynamics. Insight into mechanism evolution with increased solvation. J. Am. Chem. Soc. 140, 10995–11005 (2018).

    CAS  Article  Google Scholar 

  27. 27.

    Mugnai, M., Cardini, G. & Schettino, V. Substitution and elimination reaction of F with C2H5Cl: An ab initio molecular dynamics study. J. Phys. Chem. A 107, 2540–2547 (2003).

    CAS  Article  Google Scholar 

  28. 28.

    Stei, M. et al. Influence of the leaving group on the dynamics of a gas-phase SN2 reaction. Nat. Chem. 8, 151–156 (2016).

    CAS  Article  Google Scholar 

  29. 29.

    Mikosch, J. et al. Imaging nucleophilic substitution dynamics. Science 319, 183–186 (2008).

    CAS  Article  Google Scholar 

  30. 30.

    Carrascosa, E., Meyer, J., Michaelsen, T., Stei, M. & Wester, R. Conservation of direct dynamics in sterically hindered SN2/E2 reactions. Chem. Sci. 9, 693–701 (2018).

    CAS  Article  Google Scholar 

  31. 31.

    Zhang, J., Xie, J. & Hase, W. L. Dynamics of the F + CH3I → HF + CH2I proton transfer reaction. J. Phys. Chem. A 119, 12517–12525 (2015).

    CAS  Article  Google Scholar 

  32. 32.

    Walden, P. Über die gegenseitige Umwandlung optischer Antipoden. Ber. Dtsch. Chem. Ges. 29, 133–138 (1896).

    Article  Google Scholar 

  33. 33.

    Eppink, A. T. J. B. & Parker, D. H. Velocity map imaging of ions and electrons using electrostatic lenses: Application in photoelectron and photofragment ion imaging of molecular oxygen. Rev. Sci. Instrum. 68, 3477–3484 (1997).

    CAS  Article  Google Scholar 

  34. 34.

    Wester, R. Velocity map imaging of ion–molecule reactions. Phys. Chem. Chem. Phys. 16, 396–405 (2014).

    CAS  Article  Google Scholar 

  35. 35.

    Bastian, B. et al. Imaging reaction dynamics of F(H2O) and Cl(H2O) with CH3I. J. Phys. Chem. A 124, 1929–1939 (2020).

    CAS  Article  Google Scholar 

  36. 36.

    Fateley, W. G. & Miller, F. A. Torsional frequencies in the far infrared - III: The form of the potential curve for hindered internal rotation of a methyl group. Spectrochim. Acta 19, 611–628 (1963).

    CAS  Article  Google Scholar 

  37. 37.

    Győri, T. & Czakó, G. Automating the development of high-dimensional reactive potential energy surfaces with the ROBOSURFER program system. J. Chem. Theory Comput. 16, 51–66 (2020).

    Article  Google Scholar 

  38. 38.

    Xie, Z. & Bowman, J. M. Permutationally invariant polynomial basis for molecular energy surface fitting via monomial symmetrization. J. Chem. Theory Comput. 6, 26–34 (2010).

    CAS  Article  Google Scholar 

  39. 39.

    Werner, H.-J. et al. Molpro, v.2015.1 (Molpro, 2015);

  40. 40.

    Hase, W. L. in Encyclopedia of Computational Chemistry Vol. 1 (ed. Allinger, N. L.) 399–407 (Wiley, 1998).

Download references


R.W. thanks the Austrian Science Fund (FWF), project P25956-N20, for support of this work. G.C. thanks the National Research, Development and Innovation Office-NKFIH, K-125317, the Ministry of Human Capacities, Hungary grant 20391-3/2018/FEKUSTRAT and the Momentum (Lendület) Program of the Hungarian Academy of Sciences for financial support. We acknowledge KIFÜ for awarding us access to computational resources based at Debrecen in Hungary. J.M. acknowledges support from a Hertha Firnberg Fellowship of the Austrian Science Fund (T962-N34). E.C. acknowledges support from the DOC Fellowship of the Austrian Academy of Science.

Author information




E.C., J.M. and M.S. carried out the experiment. J.M. and E.C. analysed the data. B.B. extended the data analysis program suite. T.M. and B.B. contributed to data discussion and interpretation. V.T. and T.G. developed the potential energy surface. V.T. performed the trajectory simulations and analysed the data. G.C. and R.W. supervised the project. J.M. and R.W. prepared the manuscript. V.T. and G.C. contributed the theoretical sections.

Corresponding authors

Correspondence to Gábor Czakó or Roland Wester.

Ethics declarations

Competing interests

The authors declare no competing interests.

Additional information

Peer review information Nature Chemistry thanks Piergiorgio Casavecchia, Dunyou Wang and Xingan Wang for their contribution to the peer review of this work.

Publisher’s note Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.

Supplementary information

Supplementary Information

Supplementary Materials and Methods, Figs. 1–10.

Supplementary Data 1

Source data to support the plots in the Supplementary Information file.

Supplementary Data 2

Initial and final QCT coordinates, 0.35 eV.

Supplementary Data 3

Initial and final QCT coordinates, 0.83 eV.

Supplementary Data 4

Initial and final QCT coordinates, 1.15 eV.

Supplementary Data 5

Initial and final QCT coordinates, 1.6 eV.

Supplementary Data 6

Initial and final QCT coordinates, 1.98 eV.

Source data

Source Data Fig. 2

Source data for Fig. 2.

Source Data Fig. 3

Source data for Fig. 3.

Source Data Fig. 4

Source data for Fig. 4.

Rights and permissions

Reprints and Permissions

About this article

Verify currency and authenticity via CrossMark

Cite this article

Meyer, J., Tajti, V., Carrascosa, E. et al. Atomistic dynamics of elimination and nucleophilic substitution disentangled for the F + CH3CH2Cl reaction. Nat. Chem. 13, 977–981 (2021).

Download citation


Quick links

Nature Briefing

Sign up for the Nature Briefing newsletter — what matters in science, free to your inbox daily.

Get the most important science stories of the day, free in your inbox. Sign up for Nature Briefing