Stretching vibration is a spectator in nucleophilic substitution

Stei, Martin; Carrascosa, Eduardo; Dörfler, Alexander; Meyer, Jennifer; Olasz, Balázs; Czakó, Gábor; Li, Anyang; Guo, Hua; Wester, Roland

doi:10.1126/sciadv.aas9544

Cited by 44 publications

(76 citation statements)

References 43 publications

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“…To gain insight how the enhancement depends on the collision energy, we have calculated the branching ratios for proton transfer relative to S N 2 products at similar total energies, i.e., collision energy plus energy in the vibrational mode. Assuming no change in the S N 2 channel due to vibrational excitation, 28 the branching ratios yield insight whether translation or vibration is more efficient in promoting reactivity. At the highest collision energy the assumption of spectator mode S N 2 dynamics is not strictly correct, as we recently found a small but significant enhancement of the S N 2 channel, which will be discussed in a separate publication.…”

Section: Collision Energy Pt Counts Ir Off Pt Counts Ir Onmentioning

confidence: 99%

“…The points for excited reactions are scaled to 100% excitation in the neutral beam. The grey points 27 and the light blue (ground state) and pink points (vibrationally excited) 28 are from previous studies by our group. Points shown in blue are for ground state and in red for vibrationally excited reactions.…”

Section: Comparison With Theorymentioning

confidence: 99%

“…E-mail: roland.wester@uibk.ac.at; Tel: +43 512 507 52620 by SVP and QCT calculations. 28 For the proton transfer reaction the situation is different and more similar to neutral halide reactions with CHD 3 , 19 as we excite the bond that is broken during the reaction. This leads to interesting questions: Is vibration more efficient in promoting the reaction compared to collision energy and if so, does the enhancement depend on the collision energy?…”

Section: Introductionmentioning

confidence: 96%

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Proton transfer dynamics modified by CH-stretching excitation

Michaelsen

Bastian

Strübin

et al. 2020

Phys. Chem. Chem. Phys.

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Gaining insight how specific rovibrational states influence reaction kinetics and dynamics is a fundamental goal of physical chemistry. Purely statistical approaches often fail to predict the influence of a specific state on the reaction outcome, evident in a great number of both experimental and theoretical studies. Most detailed insight in atomistic reaction mechanisms is achieved using accurate collision experiments and high level dynamics calculations. For ion-molecule reactions such experiments are scarce. Here we show the influence of symmetric CH-stretching vibration on the rate and dynamics of proton transfer in the reaction of F À + CH 3 I. We find a pronounced shift in the reaction dynamics for excited reactions from indirect to preferred direct dynamics at higher collision energy. Moreover, excited reactions occur at larger impact parameters. Finally, we compare vibrational excitation with collision energy and find that vibration is overall more efficient in promoting reactivity, which agrees with recent theoretical calculations.

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Section: Collision Energy Pt Counts Ir Off Pt Counts Ir Onmentioning

confidence: 99%

Section: Comparison With Theorymentioning

confidence: 99%

Section: Introductionmentioning

confidence: 96%

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Proton transfer dynamics modified by CH-stretching excitation

Michaelsen

Bastian

Strübin

et al. 2020

Phys. Chem. Chem. Phys.

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“…This is also in agreement with the previous findings that the mode specific excitation of the CH3 deformation does not promote the SN2 reaction [25][26][27][28][29][30][31] and excitation of CH symmetric stretching modes is ineffective to SN2 reaction as shown in a recent experimental study. 102 We stress once more that this conclusion has been reached with a quantum mechanical approximate method and employing 500,000 classical trajectories.…”

Section: Understanding Couplings Between the Vibrational Modesmentioning

confidence: 74%

A quantum mechanical insight into SN2 reactions: Semiclassical initial value representation calculations of vibrational features of the Cl−⋯CH3Cl pre-reaction complex with the VENUS suite of codes

Liberto

Conte

et al. 2018

The Journal of Chemical Physics

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The role of vibrational excitation of reactants in driving reactions involving polyatomic species has been often studied by means of classical or quasi-classical trajectory simulations. We propose a different approach based on investigation of vibrational features of the Cl ----CH3Cl prereaction complex for the Cl -+ CH3Cl SN2 reaction. We present vibrational power spectra and frequency estimates for the title pre-reaction complex calculated at the level of classical, semiclassical, and second-order vibrational perturbation theory on a pre-existing analytical potential energy surface. The main goals of the paper are the study of anharmonic effects and understanding of vibrational couplings that permit energy transfer between the collisional kinetic energy and the internal vibrations of the reactants. We provide both classical and quantum pictures of intermode couplings, and show that the SN2 mechanism is favored by coupling of a C-Cl bend involving the Clprojectile with the CH3 rocking motion of the target molecule. We also illustrate how the routines needed for semiclassical vibrational spectroscopy simulations can be interfaced in a user-friendly way to pre-existing molecular dynamics software. In particular, we present implementation of semiclassical spectroscopy into the VENUS suite of codes, thus providing a useful computational tool for users who are not experts of semiclassical dynamics.

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“…2018-ban pedig egy újabb elméleti-kísérleti együttmûködés keretében vizsgáltuk a F -+ CH 3 I reakció módspecifikus dinamikáját, amit a rangos Science Advances folyóirat közölt. 4 Az S N 2 reakciók dinamikájának területén elért eredményeinkrõl az érdeklõdõ olvasó részletesebben is tájékozódhat a Journal of Physical Chemistry folyóirat szerkesztõjének felkérésére írt összefoglaló cikkünkbõl, 22 amit az újság a címlapján emelt ki.…”

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