1
|
Tasi DA, Czakó G. Vibrational mode-specificity in the dynamics of the OH- + CH3I multi-channel reaction. J Chem Phys 2024; 160:044305. [PMID: 38265083 DOI: 10.1063/5.0189561] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2023] [Accepted: 12/25/2023] [Indexed: 01/25/2024] Open
Abstract
We report a comprehensive characterization of the vibrational mode-specific dynamics of the OH- + CH3I reaction. Quasi-classical trajectory simulations are performed at four different collision energies on our previously-developed full-dimensional high-level ab initio potential energy surface in order to examine the impact of four different normal-mode excitations in the reactants. Considering the 11 possible pathways of OH- + CH3I, pronounced mode-specificity is observed in reactivity: In general, the excitations of the OH- stretching and CH stretching exert the greatest influence on the channels. For the SN2 and proton-abstraction products, the reactant initial attack angle and the product scattering angle distributions do not show major mode-specific features, except for SN2 at higher collision energies, where forward scattering is promoted by the CI stretching and CH stretching excitations. The post-reaction energy flow is also examined for SN2 and proton abstraction, and it is unveiled that the excess vibrational excitation energies rather transfer into the product vibrational energy because the translational and rotational energy distributions of the products do not represent significant mode-specificity. Moreover, in the course of proton abstraction, the surplus vibrational energy in the OH- reactant mostly remains in the H2O product owing to the prevailing dominance of the direct stripping mechanism.
Collapse
Affiliation(s)
- Domonkos A Tasi
- MTA-SZTE Lendület Computational Reaction Dynamics Research Group, Interdisciplinary Excellence Centre and Department of Physical Chemistry and Materials Science, Institute of Chemistry, University of Szeged, Rerrich Béla tér 1, Szeged H-6720, Hungary
| | - Gábor Czakó
- MTA-SZTE Lendület Computational Reaction Dynamics Research Group, Interdisciplinary Excellence Centre and Department of Physical Chemistry and Materials Science, Institute of Chemistry, University of Szeged, Rerrich Béla tér 1, Szeged H-6720, Hungary
| |
Collapse
|
2
|
Tajti V, Czakó G. Vibrational mode-specific dynamics of the F - + CH 3CH 2Cl multi-channel reaction. Phys Chem Chem Phys 2022; 24:8166-8181. [PMID: 35343535 DOI: 10.1039/d2cp00685e] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
We investigate the mode-specific dynamics of the ground-state, C-Cl stretching (v10), CH2 wagging (v7), sym-CH2 stretching (v1), and sym-CH3 stretching (v3) excited F- + CH3CH2Cl(vk = 0, 1) [k = 10, 7, 1, 3] → Cl- + CH3CH2F (SN2), HF + CH3CHCl-, FH⋯Cl- + C2H4, and Cl- + HF + C2H4 (E2) reactions using a full-dimensional high-level analytical global potential energy surface and the quasi-classical trajectory method. Excitation of the C-Cl stretching, CH2 stretching, and CH2/CH3 stretching modes enhances the SN2, proton abstraction, and FH⋯Cl- and E2 channels, respectively. Anti-E2 dominates over syn-E2 (kinetic anti-E2 preference) and the thermodynamically-favored SN2 (wider reactive anti-E2 attack angle range). The direct (a) SN2, (b) proton abstraction, (c) FH⋯Cl- + C2H4, (d) syn-E2, and (e) anti-E2 channels proceed with (a) back-side/backward, (b) isotropic/forward, (c) side-on/forward, (d) front-side/forward, and (e) back-side/forward attack/scattering, respectively. The HF products are vibrationally cold, especially for proton abstraction, and their rotational excitation increases for proton abstraction, anti-E2, and syn-E2, in order. Product internal-energy and mode-specific vibrational distributions show that CH3CH2F is internally hot with significant C-F stretching and CH2 wagging excitations, whereas C2H4 is colder. One-dimensional Gaussian binning technique is proved to solve the normal mode analysis failure caused by methyl internal rotation.
Collapse
Affiliation(s)
- Viktor Tajti
- MTA-SZTE Lendület Computational Reaction Dynamics Research Group, Interdisciplinary Excellence Centre and Department of Physical Chemistry and Materials Science, Institute of Chemistry, University of Szeged, Rerrich Béla tér 1, Szeged H-6720, Hungary.
| | - Gábor Czakó
- MTA-SZTE Lendület Computational Reaction Dynamics Research Group, Interdisciplinary Excellence Centre and Department of Physical Chemistry and Materials Science, Institute of Chemistry, University of Szeged, Rerrich Béla tér 1, Szeged H-6720, Hungary.
| |
Collapse
|
3
|
Mode Specificity Dynamics of the Prototypical Multi-Channel H+CH 3OH Reaction on a Globally Accurate Potential Energy Surface. CHINESE J CHEM PHYS 2022. [DOI: 10.1063/1674-0068/cjcp2201018] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
|
4
|
Meng F, Li Y, Wang D. Predicting atomic-level reaction mechanisms for S N2 reactions via machine learning. J Chem Phys 2021; 155:224111. [PMID: 34911303 DOI: 10.1063/5.0074422] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Abstract
Identifying atomic-level reaction mechanisms is an essential step in chemistry. In this study, we develop a joint-voting model based on three parallel machine-learning algorithms to predict atomic-level and dynamical mechanisms trained with 1700 trajectories. Three predictive experiments are carried out with the training trajectories divided into ten, seven, and five classes. The results indicate that, as the number of trajectories in each class increases from the ten- to five-class model, the five-class model converges the fastest and the prediction success rate increases. The number of trajectories in each experiment to get the predictive models converged is 100, 100, and 70, respectively. The prediction accuracy increases from 88.3% for the ten-class experiment, to 91.0% for the seven-class, and to 92.0% for the five-class. Our study demonstrates that machine learning can also be used to predict elementary dynamical processes of structural evolution along time, that is, atomic-level reaction mechanisms.
Collapse
Affiliation(s)
- Fanbin Meng
- School of Medical Information Engineering, Jining Medical University, Jining 272067, Shandong, China
| | - Yan Li
- College of Physics and Electronics, Shandong Normal University, Jinan 250014, Shandong, China
| | - Dunyou Wang
- College of Physics and Electronics, Shandong Normal University, Jinan 250014, Shandong, China
| |
Collapse
|
5
|
Wester R. Fifty years of nucleophilic substitution in the gas phase. MASS SPECTROMETRY REVIEWS 2021; 41:627-644. [PMID: 34060119 PMCID: PMC9291629 DOI: 10.1002/mas.21705] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/31/2021] [Revised: 05/05/2021] [Accepted: 05/05/2021] [Indexed: 06/12/2023]
Abstract
Bimolecular nucleophilic substitution ( S N 2 ) reactions have become a model system for the investigation of structure-reactivity relationships, stereochemistry, solvent influences, and detailed atomistic dynamics. In this review, the progress during five decades of experimental and theoretical research on gas phase S N 2 reactions is discussed. Many advancements of the employed methods have led to a tremendous increase in our understanding of the properties and the dynamics of these reactions. For reactions involving six atoms a quantitative agreement of the differential reactive scattering cross sections has already been achieved, in the future it is expected that even larger polyatomic reactions systems become tractable. Furthermore, studies with higher precision, improved reactant control, and a more accurate theoretical treatment of quantum effects are envisioned.
Collapse
Affiliation(s)
- Roland Wester
- Institut für Ionenphysik und Angewandte PhysikUniversität InnsbruckTechnikerstraße 256020 InnsbruckAustria
| |
Collapse
|
6
|
Papp P, Czakó G. Rotational Mode Specificity in the F - + CH 3I( v = 0, JK) S N2 and Proton-Transfer Reactions. J Phys Chem A 2020; 124:8943-8948. [PMID: 33054214 PMCID: PMC7604870 DOI: 10.1021/acs.jpca.0c08043] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
![]()
Quasiclassical
trajectory computations are performed for the F– + CH3I(v = 0, JK) →
I– + CH3F (SN2) and HF + CH2I– (proton-transfer)
reactions considering initial rotational states characterized by J = {0, 2, 4, 6, 8, 12, and 16} and K =
{0 and J} in the 1–30 kcal/mol collision energy
(Ecoll) range. Tumbling rotation (K = 0) counteracts orientation effects, thereby hindering
the SN2 reactivity by about 15% for J =
16 in the 1–15 kcal/mol Ecoll range
and has a negligible effect on proton transfer. Spinning about the
C–I bond (K = J), which is
21 times faster than tumbling, makes the reactions more direct, inhibiting
the SN2 reactivity by 25% in some cases, whereas significantly
enhancing the proton-transfer channel by a factor of 2 at Ecoll = 15 kcal/mol due to the fact that the
spinning-induced centrifugal force hinders complex formation by breaking
H-bonds and activates C–H bond cleavage, thereby promoting
proton abstraction on the expense of substitution. At higher Ecoll, as the reactions become more direct, the
rotational effects are diminishing.
Collapse
Affiliation(s)
- Paszkál Papp
- MTA-SZTE Lendület Computational Reaction Dynamics Research Group, Interdisciplinary Excellence Centre and Department of Physical Chemistry and Materials Science, Institute of Chemistry, University of Szeged, Rerrich Béla tér 1, Szeged H-6720, Hungary
| | - Gábor Czakó
- MTA-SZTE Lendület Computational Reaction Dynamics Research Group, Interdisciplinary Excellence Centre and Department of Physical Chemistry and Materials Science, Institute of Chemistry, University of Szeged, Rerrich Béla tér 1, Szeged H-6720, Hungary
| |
Collapse
|
7
|
Li J, Zhao B, Xie D, Guo H. Advances and New Challenges to Bimolecular Reaction Dynamics Theory. J Phys Chem Lett 2020; 11:8844-8860. [PMID: 32970441 DOI: 10.1021/acs.jpclett.0c02501] [Citation(s) in RCA: 32] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
Dynamics of bimolecular reactions in the gas phase are of foundational importance in combustion, atmospheric chemistry, interstellar chemistry, and plasma chemistry. These collision-induced chemical transformations are a sensitive probe of the underlying potential energy surface(s). Despite tremendous progress in past decades, our understanding is still not complete. In this Perspective, we survey the recent advances in theoretical characterization of bimolecular reaction dynamics, stimulated by new experimental observations, and identify key new challenges.
Collapse
Affiliation(s)
- Jun Li
- School of Chemistry and Chemical Engineering & Chongqing Key Laboratory of Theoretical and Computational Chemistry, Chongqing University, Chongqing 401331, China
| | - Bin Zhao
- Theoretische Chemie, Fakultät für Chemie, Universität Bielefeld, Universitätsstraße 25, D-33615 Bielefeld, Germany
| | - Daiqian Xie
- Institute of Theoretical and Computational Chemistry, School of Chemistry and Chemical Engineering, Nanjing University, Nanjing 210023, China
| | - Hua Guo
- Department of Chemistry and Chemical Biology, University of New Mexico, Albuquerque, New Mexico 87131, United States
| |
Collapse
|
8
|
Numerical separation of the front-side attack and double-inversion retention pathways of SN2 reactions. Chem Phys Lett 2020. [DOI: 10.1016/j.cplett.2020.137780] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
|
9
|
Li Y, Li Y, Wang D. The importance of the composite mechanisms with two transition states in the F - + NH 2I S N2 reaction. Phys Chem Chem Phys 2020; 22:12929-12938. [PMID: 32453309 DOI: 10.1039/d0cp01942a] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The dynamics of the bimolecular nucleophilic substitution (SN2) reactions at nitrogen are less understood than those of their corresponding reactions at carbon. In this paper, we report an ab initio molecular dynamics approach to investigate the reaction mechanisms of the F- + NH2I SN2 reaction at nitrogen. We found not only the one-transition-state mechanisms, but also the composite mechanisms with two and three transition states. For the two-transition-state mechanisms, the double inversion mechanism and the proton-abstraction roundabout followed by the backside-attack reaction mechanism have been reported before; but we discovered that there is also a new, front-side attack followed by the backside-attack Walden-inversion mechanism. Furthermore, a composite mechanism with three transition states also shows up in the reactive trajectories. Our results show that, as the collision energy increases, the SN2 reactivity decreases, and the proton-abstraction reactivity increases. The two-transition-state mechanisms, especially the double-inversion mechanism, make the largest contribution to the SN2 reactivity, followed then by the one-transition-state mechanisms, with the three-transition-state mechanism contributing the least. The potential energy profiles of the reaction mechanisms are characterized at the CCSD(T)/aug-cc-pVTZ(PP) level of theory. The analysis on stationary points shows that the proton-abstraction inversion transition state is ∼12.4 kcal mol-1 lower than the Walden-inversion transition state in contrast to the corresponding reaction at carbon F- + CH3I, in which the former is ∼26.1 kcal mol-1 higher than the latter. This might explain why the composite mechanism of the double inversion mechanism contributes the most to the SN2 reactivity in the F- + NH2I reaction.
Collapse
Affiliation(s)
- Yan Li
- College of Physics and Electronics, Shandong Normal University, Jinan 250014, Shandong, China.
| | | | | |
Collapse
|
10
|
Michaelsen T, Bastian B, Strübin P, Meyer J, Wester R. Proton transfer dynamics modified by CH-stretching excitation. Phys Chem Chem Phys 2020; 22:12382-12388. [PMID: 32319988 DOI: 10.1039/d0cp00727g] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
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- + CH3I. 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.
Collapse
Affiliation(s)
- Tim Michaelsen
- Institut für Ionenphysik und Angewandte Physik, Universität Innsbruck, Technikerstraße 25/3, 6020 Innsbruck, Austria.
| | - Björn Bastian
- Institut für Ionenphysik und Angewandte Physik, Universität Innsbruck, Technikerstraße 25/3, 6020 Innsbruck, Austria.
| | - Patrick Strübin
- Institut für Ionenphysik und Angewandte Physik, Universität Innsbruck, Technikerstraße 25/3, 6020 Innsbruck, Austria.
| | - Jennifer Meyer
- Institut für Ionenphysik und Angewandte Physik, Universität Innsbruck, Technikerstraße 25/3, 6020 Innsbruck, Austria.
| | - Roland Wester
- Institut für Ionenphysik und Angewandte Physik, Universität Innsbruck, Technikerstraße 25/3, 6020 Innsbruck, Austria.
| |
Collapse
|
11
|
Michaelsen T, Bastian B, Ayasli A, Strübin P, Meyer J, Wester R. Influence of Vibrational Excitation on the Reaction of F - with CH 3I: Spectator Mode Behavior, Enhancement, and Suppression. J Phys Chem Lett 2020; 11:4331-4336. [PMID: 32383877 PMCID: PMC7277560 DOI: 10.1021/acs.jpclett.0c01095] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2020] [Accepted: 05/04/2020] [Indexed: 06/10/2023]
Abstract
Detailed insight into chemical reaction dynamics can be obtained by probing the effect of mode-specific vibrational excitation. Suppression or enhancement of reactivity is possible as is already known from the Polanyi rules. In the reaction F- + CH3I, we found vibrational enhancement, suppression, and spectator mode dynamics in the four different reaction channels. For this system we have probed the influence of symmetric CH-stretching vibration over a collision energy range of 0.7-2.3 eV. Proton transfer is significantly enhanced, while for the nucleophilic substitution channel the spectator mode dynamics at lower collision energies unexpectedly move toward enhancement at higher collision energies. In contrast, for two halide abstraction channels, forming FI- and FHI-, we found an overall suppression, which stems mainly from a suppression of the FHI- product. We compare these results to quasiclassical trajectory calculations and with the sudden vector projection model.
Collapse
Affiliation(s)
- Tim Michaelsen
- Institut für Ionenphysik und Angewandte Physik, Universität Innsbruck, Technikerstraße 25/3, 6020 Innsbruck, Austria
| | - Björn Bastian
- Institut für Ionenphysik und Angewandte Physik, Universität Innsbruck, Technikerstraße 25/3, 6020 Innsbruck, Austria
| | - Atilay Ayasli
- Institut für Ionenphysik und Angewandte Physik, Universität Innsbruck, Technikerstraße 25/3, 6020 Innsbruck, Austria
| | - Patrick Strübin
- Institut für Ionenphysik und Angewandte Physik, Universität Innsbruck, Technikerstraße 25/3, 6020 Innsbruck, Austria
| | - Jennifer Meyer
- Institut für Ionenphysik und Angewandte Physik, Universität Innsbruck, Technikerstraße 25/3, 6020 Innsbruck, Austria
| | - Roland Wester
- Institut für Ionenphysik und Angewandte Physik, Universität Innsbruck, Technikerstraße 25/3, 6020 Innsbruck, Austria
| |
Collapse
|
12
|
Bastian B, Michaelsen T, Ončák M, Meyer J, Wester R. F−(H2O)+CH3I ligand exchange reaction dynamics. CHINESE J CHEM PHYS 2020. [DOI: 10.1063/1674-0068/cjcp2002018] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022]
Affiliation(s)
- Björn Bastian
- Institut für Ionenphysik und Angewandte Physik, Universität Innsbruck, Technikerstraße 25, 6020 Innsbruck, Austria
| | - Tim Michaelsen
- Institut für Ionenphysik und Angewandte Physik, Universität Innsbruck, Technikerstraße 25, 6020 Innsbruck, Austria
| | - Milan Ončák
- Institut für Ionenphysik und Angewandte Physik, Universität Innsbruck, Technikerstraße 25, 6020 Innsbruck, Austria
| | - Jennifer Meyer
- Institut für Ionenphysik und Angewandte Physik, Universität Innsbruck, Technikerstraße 25, 6020 Innsbruck, Austria
| | - Roland Wester
- Institut für Ionenphysik und Angewandte Physik, Universität Innsbruck, Technikerstraße 25, 6020 Innsbruck, Austria
| |
Collapse
|