1
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Gstir T, Sundelin D, Michaelsen T, Ayasli A, Swaraj D, Judy J, Zappa F, Geppert W, Wester R. Reaction dynamics of the methoxy anion CH 3O - with methyl iodide CH 3I. Faraday Discuss 2024; 251:573-586. [PMID: 38770842 PMCID: PMC11349062 DOI: 10.1039/d3fd00164d] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2023] [Accepted: 02/07/2024] [Indexed: 05/22/2024]
Abstract
Studying larger nucleophiles in bimolecular nucleophilic substitution (SN2) reactions bridges the gap from simple model systems to those relevant to organic chemistry. Therefore, we investigated the reaction dynamics between the methoxy anion (CH3O-) and iodomethane (CH3I) in our crossed-beam setup combined with velocity map imaging at the four collision energies 0.4, 0.7, 1.2, and 1.6 eV. We find the two ionic products I- and CH2I-, which can be attributed to the SN2 and proton transfer channels, respectively. The proton transfer channel progresses in a previously observed fashion from indirect to direct scattering with increasing collision energy. Interestingly, the SN2 channel exhibits direct dynamics already at low collision energies. Both the direct stripping, leading to forward scattering, and the direct rebound mechanism, leading to backward scattering into high angles, are observed.
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Affiliation(s)
- Thomas Gstir
- Institut für Ionenphysik und Angewandte Physik, Universität Innsbruck, 6020 Innsbruck, Austria.
| | - David Sundelin
- Department of Physics, Stockholm University, 106 91 Stockholm, Sweden
| | - Tim Michaelsen
- Institut für Ionenphysik und Angewandte Physik, Universität Innsbruck, 6020 Innsbruck, Austria.
| | - Atilay Ayasli
- Institut für Ionenphysik und Angewandte Physik, Universität Innsbruck, 6020 Innsbruck, Austria.
| | - Dasarath Swaraj
- Institut für Ionenphysik und Angewandte Physik, Universität Innsbruck, 6020 Innsbruck, Austria.
| | - Jerin Judy
- Institut für Ionenphysik und Angewandte Physik, Universität Innsbruck, 6020 Innsbruck, Austria.
| | - Fabio Zappa
- Institut für Ionenphysik und Angewandte Physik, Universität Innsbruck, 6020 Innsbruck, Austria.
| | - Wolf Geppert
- Department of Physics, Stockholm University, 106 91 Stockholm, Sweden
| | - Roland Wester
- Institut für Ionenphysik und Angewandte Physik, Universität Innsbruck, 6020 Innsbruck, Austria.
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2
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Tasi DA, Czakó G. Benchmark ab initio characterization of the complex potential energy surfaces of the HOO - + CH 3Y [Y = F, Cl, Br, I] reactions. Phys Chem Chem Phys 2024; 26:16048-16059. [PMID: 38779842 DOI: 10.1039/d4cp01071j] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/25/2024]
Abstract
The α-effect is a well-known phenomenon in organic chemistry, and is related to the enhanced reactivity of nucleophiles involving one or more lone-pair electrons adjacent to the nucleophilic center. The gas-phase bimolecular nucleophilic substitution (SN2) reactions of α-nucleophile HOO- with methyl halides have been thoroughly investigated experimentally and theoretically; however, these investigations have mainly focused on identifying and characterizing the α-effect of HOO-. Here, we perform the first comprehensive high-level ab initio mapping for the HOO- + CH3Y [Y = F, Cl, Br and I] reactions utilizing the modern explicitly-correlated CCSD(T)-F12b method with the aug-cc-pVnZ [n = 2-4] basis sets. The present ab initio characterization considers five distinct product channels of SN2: (CH3OOH + Y-), proton abstraction (CH2Y- + H2O2), peroxide ion substitution (CH3OO- + HY), SN2-induced elimination (CH2O + HY + HO-) and SN2-induced rearrangement (CH2(OH)O- + HY). Moreover, besides the traditional back-side attack Walden inversion, the pathways of front-side attack, double inversion and halogen-bond complex formation have also been explored for SN2. With regard to the Walden inversion of HOO- + CH3Cl, the previously unaddressed discrepancies concerning the geometry of the corresponding transition state are clarified. For the HOO- + CH3F reaction, the recently identified SN2-induced elimination is found to be more exothermic than the SN2 channel, submerged by ∼36 kcal mol-1. The accuracy of our high-level ab initio calculations performed in the present study is validated by the fact that our new benchmark 0 K reaction enthalpies show excellent agreement with the experimental data in nearly all cases.
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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.
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3
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Liu X, Feng H, Li R, Zhang Q, Wu Y, Pang B. Mechanistic Insights into the Proton Transfer and Substitution Dynamics of N-Atom Center Reactions: A Study of CH 3O - with NH 2Cl. J Phys Chem A 2024. [PMID: 38502933 DOI: 10.1021/acs.jpca.3c08447] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/21/2024]
Abstract
Bimolecular substitution reactions involving N as the central atom have continuously improved our understanding of substitution dynamics. This work used chemical dynamics simulations to investigate the dynamics of NH2Cl with N as the central atom and the multiatomic nucleophile CH3O- and compared these results with the F- + NH2Cl reaction. The most noteworthy difference is in the competition between proton transfer (PT) and the SN2 pathways. Our results demonstrate that, for the CH3O- + NH2Cl system, the PT pathway is considerably more favorable than the SN2 pathway. In contrast, no PT pathway was observed for the F- + NH2Cl system at room temperature. This can be attributed to the exothermic reaction of the PT pathway for the CH3O- + NH2Cl reaction and is coupled with a more stable transition state compared to the substitution pathway. Furthermore, the bulky nature of the CH3O- group impedes its participation in SN2 reactions, which enhances both the thermodynamic and the dynamic advantages of the PT reaction. Interestingly, the atomic mechanism reveals that the PT pathway is primarily governed by indirect mechanisms, similar to the SN2 pathway, with trajectories commonly trapped in the entrance channel being a prominent feature. These trajectories are often accompanied by prolonged and frequent proton exchange or proton abstraction processes. This current work provides insights into the dynamics of N-centered PT reactions, which are useful in gaining a comprehensive understanding of the dynamics behavior of similar reactions.
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Affiliation(s)
- Xu Liu
- College of Chemistry, Liaoning University, Shenyang 110036, P. R. China
| | - Huining Feng
- College of Chemistry, Liaoning University, Shenyang 110036, P. R. China
| | - Rui Li
- College of Chemistry, Liaoning University, Shenyang 110036, P. R. China
| | - Qiuju Zhang
- Key Laboratory of Advanced Fuel Cells and Electrolyzers Technology of Zhejiang Province, Ningbo Institute of Material Technology and Engineering, Chinese Academy of Sciences, Ningbo, Zhejiang 315201, China
| | - Yang Wu
- College of Chemistry, Liaoning University, Shenyang 110036, P. R. China
| | - Boxue Pang
- Key Laboratory of Ministry of Education on Safe Mining of Deep Metal Mines, School of Resources and Civil Engineering, Northeastern University, Shenyang 110819, China
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4
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Feng H, Li R, Wu Y, Liu X. Computational Insights into S N 2 and Proton Transfer Reactions of CH 3 O - with NH 2 Y and CH 3 Y. Chemphyschem 2024; 25:e202300525. [PMID: 37905393 DOI: 10.1002/cphc.202300525] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2023] [Revised: 10/30/2023] [Accepted: 10/31/2023] [Indexed: 11/02/2023]
Abstract
Bimolecular nucleophilic substitution (SN 2) reactions have been extensively studied in both theory and experiment. While research on C-centered SN 2 reactions (SN 2@C) has been ongoing, SN 2 reactions at neutral nitrogen (SN 2@N) have received increased attention in recent years. To recommend methods for dynamics simulations, the comparison for the properties of the geometries, vibrational frequencies, and energies is done between MP2 and six DFT functional calculations and experimental data as well as the high-level CCSD(T) method for CH3 O- +NH2 Cl/CH3 Cl reactions. The relative energy diagrams at the M06 method for CH3 O- with CH3 Y/NH2 Y reactions (Y=F, Cl, Br, I) in the gas and solution phase are explored to investigate the effects of the leaving groups, different reaction centers, and solvents. We mainly focus on the computational of inv-SN 2 and proton transfer (PT) pathways. The PT channel in the gas phase is more competitive than the SN 2 channel for N-center reactions, while the opposite is observed for C-centered reactions. Solvation completely inhibits the PT channel, making SN 2 the dominant pathway. Our study provides new insight into the SN 2 reaction mechanisms and rich the novel reaction model in gas-phase organic chemistry.
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Affiliation(s)
- Huining Feng
- College of Chemistry, Liaoning University, 110036, Shenyang, China
| | - Rui Li
- College of Chemistry, Liaoning University, 110036, Shenyang, China
| | - Yang Wu
- College of Chemistry, Liaoning University, 110036, Shenyang, China
| | - Xu Liu
- College of Chemistry, Liaoning University, 110036, Shenyang, China
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5
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Ballay B, Szűcs T, Papp D, Czakó G. Phosphorus-centered ion-molecule reactions: benchmark ab initio characterization of the potential energy surfaces of the X - + PH 2Y [X, Y = F, Cl, Br, I] systems. Phys Chem Chem Phys 2023; 25:28925-28940. [PMID: 37855143 DOI: 10.1039/d3cp03733a] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2023]
Abstract
In the present work we determine the benchmark relative energies and geometries of all the relevant stationary points of the X- + PH2Y [X, Y = F, Cl, Br, I] identity and non-identity reactions using state-of-the-art electronic-structure methods. These phosphorus-centered ion-molecule reactions follow two main reaction routes: bimolecular nucleophilic substitution (SN2), leading to Y- + PH2X, and proton transfer, resulting in HX + PHY- products. The SN2 route can proceed through Walden-inversion, front-side-attack retention, and double-/multiple-inversion pathways. In addition, we also identify the following product channels: H--formation, PH2-- and PH2-formation, 1PH- and 3PH-formation, H2-formation and HY + PHX- formation. The benchmark classical relative energies are obtained by taking into account the core-correlation, scalar relativistic, and post-(T) corrections, which turn out to be necessary to reach subchemical (<1 kcal mol-1) accuracy of the results. Classical relative energies are augmented with zero-point-energy contributions to gain the benchmark adiabatic energies.
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Affiliation(s)
- Boldizsár Ballay
- 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.
| | - Tímea Szűcs
- 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.
| | - Dóra 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.
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6
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Ayasli A, Khan A, Michaelsen T, Gstir T, Ončák M, Wester R. Imaging Frontside and Backside Attack in Radical Ion-Molecule Reactive Scattering. J Phys Chem A 2023. [PMID: 37354118 DOI: 10.1021/acs.jpca.3c02856] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/26/2023]
Abstract
We report on the reactive scattering of methyl iodide, CH3I, with atomic oxygen anions O-. This radical ion-molecule reaction can produce different ionic products depending on the angle of attack of the nucleophile O- on the target molecule. We present results on the backside and frontside attack of O- on CH3I, which can lead to I- and IO- products, respectively. We combine crossed-beam velocity map imaging with quantum chemical calculations to unravel the chemical reaction dynamics. Energy-dependent scattering experiments in the range of 0.3-2.0 eV relative collision energy revealed that three different reaction pathways can lead to I- products, making it the predominant observed product. Backside attack occurs via a hydrogen-bonded complex with observed indirect, forward, and sideways scattered iodide products. Halide abstraction via frontside attack produces IO-, which mainly shows isotropic and backward scattered products at low energies. IO- is observed to dissociate further to I- + O at a certain energy threshold and favors more direct dynamics at higher collision energies.
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Affiliation(s)
- Atilay Ayasli
- Institut für Ionenphysik und Angewandte Physik, Universität Innsbruck, Technikerstrasse 25/3, 6020 Innsbruck, Austria
| | - Arnab Khan
- Institut für Ionenphysik und Angewandte Physik, Universität Innsbruck, Technikerstrasse 25/3, 6020 Innsbruck, Austria
| | - Tim Michaelsen
- Institut für Ionenphysik und Angewandte Physik, Universität Innsbruck, Technikerstrasse 25/3, 6020 Innsbruck, Austria
| | - Thomas Gstir
- Institut für Ionenphysik und Angewandte Physik, Universität Innsbruck, Technikerstrasse 25/3, 6020 Innsbruck, Austria
| | - Milan Ončák
- 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
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7
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Dékány AÁ, Czakó G. Exploring the versatile reactivity of the F- + SiH3Cl system on a full-dimensional coupled-cluster potential energy surface. J Chem Phys 2023; 158:2895234. [PMID: 37290077 DOI: 10.1063/5.0153083] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2023] [Accepted: 05/18/2023] [Indexed: 06/10/2023] Open
Abstract
We develop a full-dimensional analytical potential energy surface (PES) for the F- + SiH3Cl reaction using Robosurfer for automatically sampling the configuration space, the robust [CCSD-F12b + BCCD(T) - BCCD]/aug-cc-pVTZ composite level of theory for computing the energy points, and the permutationally invariant polynomial method for fitting. Evolution of the fitting error and the percentage of the unphysical trajectories are monitored as a function of the iteration steps/number of energy points and polynomial order. Quasi-classical trajectory simulations on the new PES reveal rich dynamics resulting in high-probability SN2 (SiH3F + Cl-) and proton-transfer (SiH2Cl- + HF) products as well as several lower-probability channels, such as SiH2F- + HCl, SiH2FCl + H-, SiH2 + FHCl-, SiHFCl- + H2, SiHF + H2 + Cl-, and SiH2 + HF + Cl-. The Walden-inversion and front-side-attack-retention SN2 pathways are found to be competitive, producing nearly racemic products at high collision energies. The detailed atomic-level mechanisms of the various reaction pathways and channels as well as the accuracy of the analytical PES are analyzed along representative trajectories.
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Affiliation(s)
- Attila Á Dékány
- 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
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8
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Stabilizing Halogen-Bonded Complex between Metallic Anion and Iodide. MOLECULES (BASEL, SWITZERLAND) 2022; 27:molecules27228069. [PMID: 36432170 PMCID: PMC9692347 DOI: 10.3390/molecules27228069] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 10/29/2022] [Revised: 11/15/2022] [Accepted: 11/18/2022] [Indexed: 11/22/2022]
Abstract
Halogen bonds (XBs) between metal anions and halides have seldom been reported because metal anions are reactive for XB donors. The pyramidal-shaped Mn(CO)5- anion is a candidate metallic XB acceptor with a ligand-protected metal core that maintains the negative charge and an open site to accept XB donors. Herein, Mn(CO)5- is prepared by electrospray ionization, and its reaction with CH3I in gas phase is studied using mass spectrometry and density functional theory (DFT) calculation. The product observed experimentally at m/z = 337 is assigned as [IMn(CO)4(OCCH3)]-, which is formed by successive nucleophilic substitution and reductive elimination, instead of the halogen-bonded complex (XC) CH3-I···Mn(CO)5-, because the I···Mn interaction is weak within XC and it could be a transient species. Inspiringly, DFT calculations predict that replacing CH3I with CF3I can strengthen the halogen bonding within the XC due to the electro-withdrawing ability of F. More importantly, in so doing, the nucleophilic substitution barrier can be raised significantly, ~30 kcal/mol, thus leaving the system trapping within the XC region. In brief, the combination of a passivating metal core and the introduction of an electro-withdrawing group to the halide can enable strong halogen bonding between metallic anion and iodide.
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9
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Robinson HT, Corkish TR, Haakansson CT, Watson PD, McKinley AJ, Wild DA. Spectroscopic Study of the Br - +CH 3 I→I - +CH 3 Br S N 2 Reaction. Chemphyschem 2022; 23:e202200278. [PMID: 35708114 PMCID: PMC9804238 DOI: 10.1002/cphc.202200278] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2022] [Revised: 06/06/2022] [Indexed: 01/05/2023]
Abstract
Mass spectrometry and anion photoelectron spectroscopy have been used to study the gas-phase <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:semantics> <mml:mrow><mml:msub><mml:mi>S</mml:mi> <mml:mi>N</mml:mi></mml:msub> <mml:mn>2</mml:mn></mml:mrow> <mml:annotation>${{{\rm S}}_{{\rm N}}2}$</mml:annotation> </mml:semantics> </mml:math> reaction involving <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:semantics> <mml:msup><mml:mrow><mml:mi>B</mml:mi> <mml:mi>r</mml:mi></mml:mrow> <mml:mo>-</mml:mo></mml:msup> <mml:annotation>${{{\rm B}{\rm r}}^{-}}$</mml:annotation> </mml:semantics> </mml:math> and <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:semantics> <mml:mrow> <mml:msub><mml:mrow><mml:mi>C</mml:mi> <mml:mi>H</mml:mi></mml:mrow> <mml:mn>3</mml:mn></mml:msub> <mml:mi>I</mml:mi></mml:mrow> <mml:annotation>${{{\rm C}{\rm H}}_{3}{\rm I}}$</mml:annotation> </mml:semantics> </mml:math> . The anion photoelectron spectra associated with the reaction intermediates of this <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:semantics> <mml:mrow><mml:msub><mml:mi>S</mml:mi> <mml:mi>N</mml:mi></mml:msub> <mml:mn>2</mml:mn></mml:mrow> <mml:annotation>${{{\rm S}}_{{\rm N}}2}$</mml:annotation> </mml:semantics> </mml:math> reaction are presented. High-level CCSD(T) calculations have been utilised to investigate the reaction intermediates that may form as a result of the <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:semantics> <mml:mrow><mml:msub><mml:mi>S</mml:mi> <mml:mi>N</mml:mi></mml:msub> <mml:mn>2</mml:mn></mml:mrow> <mml:annotation>${{{\rm S}}_{{\rm N}}2}$</mml:annotation> </mml:semantics> </mml:math> reaction along various different reaction pathways, including back-side attack and front-side attack. In addition, simulated vertical detachment energies of each reaction intermediate have been calculated to rationalise the photoelectron spectra.
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Affiliation(s)
- Hayden T. Robinson
- School of Molecular SciencesThe University of Western AustraliaCrawleyWestern Australia6009
| | - Timothy R. Corkish
- School of Molecular SciencesThe University of Western AustraliaCrawleyWestern Australia6009
| | | | - Peter D. Watson
- School of Molecular SciencesThe University of Western AustraliaCrawleyWestern Australia6009,Department of ChemistryUniversity of OxfordSouth Parks RoadOxfordUnited KingdomOX1 3QZ
| | - Allan J. McKinley
- School of Molecular SciencesThe University of Western AustraliaCrawleyWestern Australia6009
| | - Duncan A. Wild
- School of Molecular SciencesThe University of Western AustraliaCrawleyWestern Australia6009,School of ScienceEdith Cowan UniversityJoondalupWestern Australia6027
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10
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Lu X, Li L, Zhang X, Fu B, Xu X, Zhang DH. Dynamical Effects of S N2 Reactivity Suppression by Microsolvation: Dynamics Simulations of the F -(H 2O) + CH 3I Reaction on a 21-Dimensional Potential Energy Surface. J Phys Chem Lett 2022; 13:5253-5259. [PMID: 35674277 DOI: 10.1021/acs.jpclett.2c01323] [Citation(s) in RCA: 14] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
A comparison of atomistic dynamics between microsolvated and unsolvated reactions can expose the precise role of solvent molecules and thus provide deep insight into how solvation influences chemical reactions. Here we developed the first full-dimensional analytical potential energy surface of the F-(H2O) + CH3I reaction, which facilitates the efficient dynamics simulations on a quantitatively accurate level. The computed SN2 reactivity suppression ratio of the monosolvated F-(H2O) + CH3I reaction relative to the unsolvated F- + CH3I reaction as a function of collision energy first increases and then decreases steadily, forming an inverted-V shape, due to the combined dynamical effects of interaction time, steric hindrance, and collision-induced dehydration. Moreover, further analysis reveals that the steric effect of the F-(H2O) + CH3I reaction resulting from the single water molecule is manifested mainly in dragging the F- anion away from the central C atom, rather than shielding F- from C. Our study shows there is great potential in rigorously studying the role of the solvent in more complicated reactions.
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Affiliation(s)
- Xiaoxiao Lu
- State Key Laboratory of Molecular Reaction Dynamics and Center for Theoretical and Computational Chemistry, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian 116023, China
| | - Lulu Li
- State Key Laboratory of Molecular Reaction Dynamics and Center for Theoretical and Computational Chemistry, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian 116023, China
| | - Xiaoren Zhang
- State Key Laboratory of Molecular Reaction Dynamics and Center for Theoretical and Computational Chemistry, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian 116023, China
| | - Bina Fu
- State Key Laboratory of Molecular Reaction Dynamics and Center for Theoretical and Computational Chemistry, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian 116023, China
| | - Xin Xu
- Department of Chemistry, Fudan University, Shanghai 200433, China
| | - Dong H Zhang
- State Key Laboratory of Molecular Reaction Dynamics and Center for Theoretical and Computational Chemistry, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian 116023, China
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11
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Kerekes Z, Tasi DA, Czakó G. S N2 Reactions with an Ambident Nucleophile: A Benchmark Ab Initio Study of the CN - + CH 3Y [Y = F, Cl, Br, and I] Systems. J Phys Chem A 2022; 126:889-900. [PMID: 35107284 PMCID: PMC8859826 DOI: 10.1021/acs.jpca.1c10448] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
![]()
We characterize the
Walden-inversion, front-side attack, and double-inversion
SN2 pathways leading to Y– + CH3CN/CH3NC and the product channels of proton abstraction
(HCN/HNC + CH2Y–), hydride-ion substitution
(H– + YH2CCN/YH2CNC), halogen
abstraction (YCN–/YNC– + CH3 and YCN/YNC + CH3–), and YHCN–/YHNC– complex formation (YHCN–/YHNC– + 1CH2) of the CN– + CH3Y [Y = F, Cl, Br,
and I] reactions. Benchmark structures and frequencies are computed
at the CCSD(T)-F12b/aug-cc-pVTZ level of theory, and a composite approach
is employed to obtain relative energies with sub-chemical accuracy
considering (a) basis-set effects up to aug-cc-pVQZ, (b) post-CCSD(T)
correlation up to CCSDT(Q), (c) core correlation, (d) relativistic
effects, and (e) zero-point energy corrections. C–C bond formation
is both thermodynamically and kinetically more preferred than N–C
bond formation, though the kinetic preference is less significant.
Walden inversion proceeds via low or submerged barriers (12.1/17.9(F),
0.0/4.3(Cl), −3.9/0.1(Br), and −5.8/–1.8(I) kcal/mol
for C–C/N–C bond formation), front-side attack and double
inversion have high barriers (30–64 kcal/mol), the latter is
the lower-energy retention pathway, and the non-SN2 electronic
ground-state product channels are endothermic (ΔH0 = 31–92 kcal/mol).
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Affiliation(s)
- Zsolt Kerekes
- 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
| | - 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
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12
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Dékány AÁ, Kovács GZ, Czakó G. High-Level Systematic Ab Initio Comparison of Carbon- and Silicon-Centered S N2 Reactions. J Phys Chem A 2021; 125:9645-9657. [PMID: 34709818 PMCID: PMC8591615 DOI: 10.1021/acs.jpca.1c07574] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/02/2022]
Abstract
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We characterize the
stationary points along the Walden inversion,
front-side attack, and double-inversion pathways of the X– + CH3Y and X– + SiH3Y [X,
Y = F, Cl, Br, I] SN2 reactions using chemically accurate
CCSD(T)-F12b/aug-cc-pVnZ [n = D,
T, Q] levels of theory. At the carbon center, Walden inversion dominates
and proceeds via prereaction (X–···H3CY) and postreaction (XCH3···Y–) ion-dipole wells separated by a usually submerged
transition state (X–H3C–Y)−, front-side attack occurs over high barriers, double inversion is
the lowest-energy retention pathway for X = F, and hydrogen- (F–···HCH2Y) and halogen-bonded
(X–···YCH3) complexes
exist in the entrance channel. At the silicon center, Walden inversion
proceeds through a single minimum (X–SiH3–Y)−, the front-side attack is competitive via a usually
submerged transition state separating pre- and postreaction minima
having X–Si–Y angles close to 90°, double inversion
occurs over positive, often high barriers, and hydrogen- and halogen-bonded
complexes are not found. In addition to the SN2 channels
(Y– + CH3X/SiH3X), we report
reaction enthalpies for proton abstraction (HX + CH2Y–/SiH2Y–), hydride substitution
(H– + CH2XY/SiH2XY), XH···Y– complex formation (XH···Y– + 1CH2/1SiH2), and halogen
abstraction (XY + CH3–/SiH3– and XY– + CH3/SiH3).
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Affiliation(s)
- Attila Á Dékány
- 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
| | - Gyula Z Kovács
- 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
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13
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Tajti V, Győri T, Czakó G. Detailed quasiclassical dynamics of the F - + CH 3Br reaction on an ab initio analytical potential energy surface. J Chem Phys 2021; 155:124301. [PMID: 34598562 DOI: 10.1063/5.0065209] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
Dynamics and mechanisms of the F- + CH3Br(v = 0) → Br- + CH3F (SN2 via Walden inversion, front-side attack, and double inversion), F- + inverted-CH3Br (induced inversion), HF + CH2Br- (proton abstraction), and FH⋯Br- + 1CH2 reactions are investigated using a high-level global ab initio potential energy surface, the quasiclassical trajectory method, as well as non-standard configuration- and mode-specific analysis techniques. A vector-projection method is used to identify inversion and retention trajectories; then, a transition-state-attack-angle-based approach unambiguously separates the front-side attack and the double-inversion retention pathways. The Walden-inversion SN2 channel becomes direct rebound dominated with increasing collision energy as indicated by backward scattering, initial back-side attack preference, and the redshifting of product internal energy peaks in accord with CF stretching populations. In the minor retention and induced-inversion pathways, almost the entire available energy transfers into product rotation-vibration, and retention mainly proceeds with indirect, slow double inversion following induced inversion with about 50% probability. Proton abstraction is dominated by direct stripping (evidenced by forward scattering) with CH3-side initial attack preference, providing mainly vibrationally ground state products with significant zero-point energy violation.
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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
| | - Tibor Győri
- 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
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14
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Tasi DA, Tokaji C, Czakó G. A benchmark ab initio study of the complex potential energy surfaces of the OH - + CH 3CH 2Y [Y = F, Cl, Br, I] reactions. Phys Chem Chem Phys 2021; 23:13526-13534. [PMID: 34132273 DOI: 10.1039/d1cp01303c] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
Abstract
We provide the first benchmark characterization of the OH- + CH3CH2Y [Y = F, Cl, Br, I] reactions utilizing the high-level explicitly-correlated CCSD(T)-F12b method with the aug-cc-pVnZ [n = 2(D), 3(T), 4(Q)] basis sets. We explore and analyze the stationary points of the elimination (E2) and substitution (SN2) reactions, including anti-E2, syn-E2, back-side attack, front-side attack, and double inversion. In all cases, SN2 is thermodynamically more preferred than E2. In the entrance channel of SN2 a significant front-side complex formation is revealed, and in the product channel the global minimum of the title reactions is obtained at the hydrogen-bonded CH3CH2OHY- complex. Similar to the OH- + CH3Y reactions, double inversion can proceed via a notably lower-energy pathway than front-side attack, moreover, for Y = I double inversion becomes barrier-less. For the transition state of the anti-E2, a prominent ZPE effect emerges, giving an opportunity for a kinetically more favored pathway than back-side attack. In addition to SN2 and E2, other possible product channels are considered, and in most cases, the benchmark reaction enthalpies are in excellent agreement with the experimental data.
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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.
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15
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Zhu L, Yang H, Wong MW. Asymmetric Nucleophilic Allylation of α-Chloro Glycinate via Squaramide Anion-Abstraction Catalysis: SN1 or SN2 Mechanism, or Both? J Org Chem 2021; 86:8414-8424. [DOI: 10.1021/acs.joc.1c00839] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Affiliation(s)
- Lihan Zhu
- Department of Chemistry, National University of Singapore, 3 Science Drive 3, Singapore 117543
- Faculty of Chemistry, Northeast Normal University, Changchun 130024, China
| | - Hui Yang
- Department of Chemistry, National University of Singapore, 3 Science Drive 3, Singapore 117543
| | - Ming Wah Wong
- Department of Chemistry, National University of Singapore, 3 Science Drive 3, Singapore 117543
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16
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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.
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Affiliation(s)
- Roland Wester
- Institut für Ionenphysik und Angewandte PhysikUniversität InnsbruckTechnikerstraße 256020 InnsbruckAustria
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17
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Fugel M, Dittmer A, Kleemiss F, Grabowsky S. On the Role of Hydrogen Bonding in Gas-Phase S N2 Reactions at Silicon. J Phys Chem A 2021; 125:4070-4078. [PMID: 33974418 DOI: 10.1021/acs.jpca.1c00601] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
The shape of the potential energy surface (PES) of gas-phase SN2 reactions at silicon is determined by the type of nucleophile, the leaving group, and substituents which remain bonded to silicon. In this study, we present PES scans along the reaction coordinate of six symmetrical SN2 reactions: X- + SiR3X → XSiR3 + X-, where X = Cl or F and R = H, Me, or OMe. While the fluorine systems and the ClSiH3Cl system only give single-well PESs, ClSiMe3Cl and ClSi(OMe)3Cl give triple- and double-well PESs with stable pre- and post-reaction complexes. A complementary bonding analysis (energy decomposition analysis, quantum theory of atoms in molecules, and natural bond orbitals) reveals that the leaving group (X-) is stabilized by hydrogen bonding in the XSiMe3X and XSi(OMe)3X systems. It is shown that this so far neglected stabilizing contribution, along with σ-hole bonding, is responsible for the shapes of the PESs of ClSiMe3Cl and ClSi(OMe)3Cl in the gas phase.
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Affiliation(s)
- Malte Fugel
- Fachbereich 2-Biologie/ Chemie, Universität Bremen, Leobener Str. 3, 28359 Bremen, Germany
| | - Anneke Dittmer
- Fachbereich 2-Biologie/ Chemie, Universität Bremen, Leobener Str. 3, 28359 Bremen, Germany
| | - Florian Kleemiss
- Fachbereich 2-Biologie/ Chemie, Universität Bremen, Leobener Str. 3, 28359 Bremen, Germany.,Departement für Chemie, Biochemie und Pharmazie, Universität Bern, Freiestrasse 3, 3012 Bern, Switzerland
| | - Simon Grabowsky
- Fachbereich 2-Biologie/ Chemie, Universität Bremen, Leobener Str. 3, 28359 Bremen, Germany.,Departement für Chemie, Biochemie und Pharmazie, Universität Bern, Freiestrasse 3, 3012 Bern, Switzerland
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18
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Czakó G, Győri T, Papp D, Tajti V, Tasi DA. First-Principles Reaction Dynamics beyond Six-Atom Systems. J Phys Chem A 2021; 125:2385-2393. [PMID: 33631071 PMCID: PMC8028310 DOI: 10.1021/acs.jpca.0c11531] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2020] [Revised: 02/05/2021] [Indexed: 11/29/2022]
Abstract
Moving beyond the six-atomic benchmark systems, we discuss the new age and future of first-principles reaction dynamics, which investigates complex, multichannel chemical reactions. We describe the methodology starting from the benchmark ab initio characterization of the stationary points, followed by full-dimensional potential energy surface (PES) developments and reaction dynamics computations. We highlight our composite ab initio approach providing benchmark stationary-point properties with subchemical accuracy, the Robosurfer program system enabling automatic PES development, and applications for the Cl + C2H6, F + C2H6, and OH- + CH3I post-six-atom reactions focusing on ab initio issues and their solutions as well as showing the excellent agreement between theory and experiment.
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Affiliation(s)
- 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
| | - Tibor Győri
- 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
| | - Dóra 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
| | - 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
| | - 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
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19
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Papp D, Czakó G. Facilitated inversion complicates the stereodynamics of an S N2 reaction at nitrogen center. Chem Sci 2021; 12:5410-5418. [PMID: 34168784 PMCID: PMC8179618 DOI: 10.1039/d1sc00490e] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Bimolecular nucleophilic substitution (SN2) reactions at carbon center are well known to proceed with the stereospecific Walden-inversion mechanism. Reaction dynamics simulations on a newly developed high-level ab initio analytical potential energy surface for the F− + NH2Cl nitrogen-centered SN2 and proton-transfer reactions reveal a hydrogen-bond-formation-induced multiple-inversion mechanism undermining the stereospecificity of the N-centered SN2 channel. Unlike the analogous F− + CH3Cl SN2 reaction, F− + NH2Cl → Cl− + NH2F is indirect, producing a significant amount of NH2F with retention, as well as inverted NH2Cl during the timescale within the unperturbed NH2Cl molecule gets inverted with only low probability, showing the important role of facilitated inversions via an FH…NHCl−-like transition state. Proton transfer leading to HF + NHCl− is more direct and becomes the dominant product channel at higher collision energies. Multiple-inversion, the analogue of the double-inversion pathway recently revealed for SN2@C, is the key mechanism in SN2 at N center undermining stereospecificity.![]()
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Affiliation(s)
- Dóra 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
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20
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Ji X, Zhao C, Xie J. Investigating the role of halogen-bonded complexes in microsolvated Y−(H2O)n + CH3I SN2 reactions. Phys Chem Chem Phys 2021; 23:6349-6360. [DOI: 10.1039/d0cp06299e] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
A halogen-bonded complex pathway is computed for Y−(H2O)n + CH3I (Y = HO, F, Cl, Br, and I) ion–molecule nucleophilic substitution reactions and is compared with back-side and front-side attack pathways.
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Affiliation(s)
- Xiaoyan Ji
- Key Laboratory of Cluster Science of Ministry of Education
- School of Chemistry and Chemical Engineering
- Beijing Institute of Technology
- Beijing 100081
- China
| | - Chongyang Zhao
- Key Laboratory of Cluster Science of Ministry of Education
- School of Chemistry and Chemical Engineering
- Beijing Institute of Technology
- Beijing 100081
- China
| | - Jing Xie
- Key Laboratory of Cluster Science of Ministry of Education
- School of Chemistry and Chemical Engineering
- Beijing Institute of Technology
- Beijing 100081
- China
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21
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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.
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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
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22
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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]
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23
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Bastian B, Michaelsen T, Li L, Ončák M, Meyer J, Zhang DH, Wester R. Imaging Reaction Dynamics of F -(H 2O) and Cl -(H 2O) with CH 3I. J Phys Chem A 2020; 124:1929-1939. [PMID: 32050071 PMCID: PMC7197043 DOI: 10.1021/acs.jpca.0c00098] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
![]()
The
dynamics of microhydrated nucleophilic substitution reactions
have been studied using crossed beam velocity map imaging experiments
and quasiclassical trajectory simulations at different collision energies
between 0.3 and 2.6 eV. For F–(H2O) reacting
with CH3I, a small fraction of hydrated product ions I–(H2O) is observed at low collision energies.
This product, as well as the dominant I–, is formed
predominantly through indirect reaction mechanisms. In contrast, a
much smaller indirect fraction is determined for the unsolvated reaction.
At the largest studied collision energies, the solvated reaction is
found to also occur via a direct rebound mechanism. The measured product
angular distributions exhibit an overall good agreement with the simulated
angular distributions. Besides nucleophilic substitution, also ligand
exchange reactions forming F–(CH3I) and,
at high collision energies, proton transfer reactions are detected.
The differential scattering images reveal that the Cl–(H2O) + CH3I reaction also proceeds predominantly
via indirect reaction mechanisms.
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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
| | - Lulu Li
- State Key Laboratory of Molecular Reaction Dynamics, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian, Liaoning 116023, China
| | - 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
| | - Dong H Zhang
- State Key Laboratory of Molecular Reaction Dynamics, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian, Liaoning 116023, China
| | - Roland Wester
- Institut für Ionenphysik und Angewandte Physik, Universität Innsbruck, Technikerstraße 25, 6020 Innsbruck, Austria
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24
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Tasi DA, Győri T, Czakó G. On the development of a gold-standard potential energy surface for the OH− + CH3I reaction. Phys Chem Chem Phys 2020; 22:3775-3778. [DOI: 10.1039/c9cp07007a] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
We develop the first accurate full-dimensional ab initio PES for the OH− + CH3I SN2 and proton-transfer reactions treating the failure of CCSD(T) at certain geometries.
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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
- Szeged H-6720
| | - Tibor Győri
- 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
- Szeged H-6720
| | - 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
- Szeged H-6720
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25
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Czakó G, Győri T, Olasz B, Papp D, Szabó I, Tajti V, Tasi DA. Benchmark ab initio and dynamical characterization of the stationary points of reactive atom + alkane and SN2 potential energy surfaces. Phys Chem Chem Phys 2020; 22:4298-4312. [DOI: 10.1039/c9cp04944d] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
We review composite ab initio and dynamical methods and their applications to characterize stationary points of atom/ion + molecule reactions.
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Affiliation(s)
- 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
- Szeged H-6720
| | - Tibor Győri
- 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
- Szeged H-6720
| | - Balázs Olasz
- 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
- Szeged H-6720
| | - Dóra 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
- Szeged H-6720
| | - István Szabó
- 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
- Szeged H-6720
| | - 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
- Szeged H-6720
| | - 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
- Szeged H-6720
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26
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Niu X, Liu P, Wang D. Multilevel Quantum Mechanics and Molecular Mechanics Study of the Double-Inversion Mechanism at Nitrogen: F- + NH2Cl in Aqueous Solution. J Phys Chem A 2019; 124:141-147. [PMID: 31820988 DOI: 10.1021/acs.jpca.9b09689] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
We employ a multilevel quantum mechanics and molecular mechanics method to investigate the double-inversion mechanism of the nucleophilic substitution reaction at the N center: the F- + NH2Cl reaction in aqueous solution. We find that the structures of the stationary points along the reaction path are quite different from the ones in the gas phase owing to the hydrogen-bond interactions between the solute and the surrounding water molecules. The atomic-level evolutions of the structures and charge transfer along the reaction path show that this double-inversion mechanism consists of an upside-down proton inversion process and a Walden-inversion process. The computed potential of mean force at the coupled-cluster singles and doubles with perturbative triples (CCSD(T))/molecular mechanics (MM) level of theory has the two-inversion barrier heights, and reaction free energy at 11.7, 29.6, and 12.6 kcal/mol, agreeing well with the predicted ones at 12.6, 32.5, and 12.2 kcal/mol obtained on the basis of the gas-phase reaction path and the solvation free energies of the stationary points.
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Affiliation(s)
- Xiao Niu
- College of Physics and Electronics , Shandong Normal University , Jinan , Shandong 250014 , China
| | - Peng Liu
- College of Physics and Electronics , Shandong Normal University , Jinan , Shandong 250014 , China
| | - Dunyou Wang
- College of Physics and Electronics , Shandong Normal University , Jinan , Shandong 250014 , China
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27
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Meyer J, Carrascosa E, Michaelsen T, Bastian B, Li A, Guo H, Wester R. Unexpected Indirect Dynamics in Base-Induced Elimination. J Am Chem Soc 2019; 141:20300-20308. [DOI: 10.1021/jacs.9b10575] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Jennifer Meyer
- Institut für Ionenphysik und Angewandte Physik, Universität Innsbruck, Technikerstrasse 25, 6020 Innsbruck, Austria
| | - Eduardo Carrascosa
- 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
| | - Björn Bastian
- Institut für Ionenphysik und Angewandte Physik, Universität Innsbruck, Technikerstrasse 25, 6020 Innsbruck, Austria
| | - Anyang Li
- Key Laboratory of Synthetic and Natural Functional Molecule Chemistry, Ministry of Education, College of Chemistry and Materials Science, Northwest Universtiy, 710127 Xian, People’s Republic of China
| | - Hua Guo
- Department of Chemistry and Chemical Biology, University of New Mexico, Albuquerque, New Mexico 87131, United States
| | - Roland Wester
- Institut für Ionenphysik und Angewandte Physik, Universität Innsbruck, Technikerstrasse 25, 6020 Innsbruck, Austria
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Pai SJ, Lee HW, Han SS. Improved Description of a Coordinate Bond in the ReaxFF Reactive Force Field. J Phys Chem Lett 2019; 10:7293-7299. [PMID: 31709800 DOI: 10.1021/acs.jpclett.9b02668] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
To improve the description of a coordinate bond of the reactive force field (ReaxFF), we have developed ReaxFFcoord by explicitly incorporating the coordinate bond contribution, Ecoord, into the original ReaxFF ( Chenoweth et al. J. Phys. Chem. A 2008 , 112 , 1040 - 1053 ), in which the auxiliary functions are newly suggested to describe the plug-in behavior of lone-pair electrons from a donor atom to a vacant orbital of an acceptor atom. To validate the developed ReaxFFcoord, we tested it in various systems, including a representative coordinate bond-containing molecule, namely, carbon monoxide or ammonia borane. Although the fitting abilities of the ReaxFFcoord and original ReaxFF are similar, their molecular dynamics (MD) simulations are significantly different, where MD simulations employing ReaxFFcoord provide more realistic dynamic behaviors of atoms. It is expected that the ReaxFFcoord will significantly help ReaxFF to successfully extend its applicability to the material and biological systems, including coordinate bonds in organometallic systems.
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Affiliation(s)
- Sung Jin Pai
- Computational Science Research Center , Korea Institute of Science and Technology (KIST) , Hwarangno 14-gil 5 , Seongbuk-gu , Seoul 136-791 , Republic of Korea
| | - Hong Woo Lee
- Computational Science Research Center , Korea Institute of Science and Technology (KIST) , Hwarangno 14-gil 5 , Seongbuk-gu , Seoul 136-791 , Republic of Korea
| | - Sang Soo Han
- Computational Science Research Center , Korea Institute of Science and Technology (KIST) , Hwarangno 14-gil 5 , Seongbuk-gu , Seoul 136-791 , Republic of Korea
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Pratihar S, Nicola Barbosa Muniz MC, Ma X, Borges I, Hase WL. Pronounced changes in atomistic mechanisms for the Cl - + CH 3I S N2 reaction with increasing collision energy. Phys Chem Chem Phys 2019; 21:2039-2045. [PMID: 30633280 DOI: 10.1039/c8cp06198j] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
In a previous direct dynamics simulation of the Cl- + CH3I → ClCH3 + I- SN2 reaction, predominantly indirect and direct reaction was found at collision energies Erel of 0.20 and 0.39 eV, respectively. For the work presented here, these simulations were extended by studying the reaction dynamics from Erel of 0.15 to 0.40 eV in 0.05 eV intervals. A transition from a predominantly indirect to direct reaction is found for Erel of 0.27-0.28 eV, a finding consistent with experiment. The simulation results corroborate the understanding that in experiments indirect reaction is characterized by small product translational energies and isotropic scattering, while direct reaction has higher translational energies and anisotropic scattering. The traditional statistical theoretical model for the Cl- + CH3I SN2 reaction assumes the Cl--CH3I pre-reaction complex (A) is formed, followed by barrier crossing, and then formation of the ClCH3-I- post-reaction complex (B). This mechanism is seen in the dynamics, but the complete atomistic dynamics are much more complex. Atomistic SN2 mechanisms contain A and B, but other dynamical events consisting of barrier recrossing (br) and the roundabout (Ra), in which the CH3-moiety rotates around the heavy I-atom, are also observed. The two most important mechanisms are only formation of A and Ra + A. The simulation results are compared with simulations and experiments for Cl- + CH3Cl, Cl- + CH3Br, F- + CH3I, and OH- + CH3I.
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Affiliation(s)
- Subha Pratihar
- Department of Chemistry and Biochemistry, Texas Tech University, Lubbock, Texas 79409, USA.
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30
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Olasz B, Czakó G. Uncovering the role of the stationary points in the dynamics of the F - + CH 3I reaction. Phys Chem Chem Phys 2019; 21:1578-1586. [PMID: 30620025 DOI: 10.1039/c8cp06207b] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
We describe an analysis method which assigns geometries to stationary points along (quasi)classical trajectories. The method is applied to the F- + CH3I reaction, thereby uncovering the role of the minima and transition states in the dynamics of the SN2 inversion, SN2 retention via front-side attack and double inversion, induced inversion, and proton-transfer channels. Stationary-point probability distributions, stationary-point-specific trajectory orthogonal projections, root-mean-square distance distributions, transition probability matrices, and time evolutions of the stationary points reveal long-lived front-side (F-ICH3) and hydrogen-bonded (F-HCH2I) complexes in the entrance channel and significant post-reaction ion-dipole complex (FCH3I-) formation in the SN2 exit channel. Most of the proton-transfer stationary points (FHCH2I-) participate in all the reaction channels with larger distance deviations than the double-inversion transition state. Significant forward-backward transitions are observed between the minima and transition states indicating complex, indirect dynamics. The utility of distance and energy constraints is also investigated, thereby restricting the assignment into uniform configuration or energy ranges around the stationary points.
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Affiliation(s)
- Balázs Olasz
- 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.
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31
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Tasi DA, Fábián Z, Czakó G. Rethinking the X− + CH3Y [X = OH, SH, CN, NH2, PH2; Y = F, Cl, Br, I] SN2 reactions. Phys Chem Chem Phys 2019; 21:7924-7931. [DOI: 10.1039/c8cp07850e] [Citation(s) in RCA: 26] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Explicitly-correlated ab initio computations reveal novel inversion and retention pathways for several SN2 reactions with different nucleophiles and leaving groups.
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Affiliation(s)
- Domonkos A. Tasi
- Interdisciplinary Excellence Centre and Department of Physical Chemistry and Materials Science
- Institute of Chemistry
- University of Szeged
- Szeged H-6720
- Hungary
| | - Zita Fábián
- Interdisciplinary Excellence Centre and Department of Physical Chemistry and Materials Science
- Institute of Chemistry
- University of Szeged
- Szeged H-6720
- Hungary
| | - Gábor Czakó
- Interdisciplinary Excellence Centre and Department of Physical Chemistry and Materials Science
- Institute of Chemistry
- University of Szeged
- Szeged H-6720
- Hungary
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32
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Olasz B, Czakó G. Mode-Specific Quasiclassical Dynamics of the F - + CH 3I S N2 and Proton-Transfer Reactions. J Phys Chem A 2018; 122:8143-8151. [PMID: 30230832 DOI: 10.1021/acs.jpca.8b08286] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Mode-specific quasiclassical trajectory computations are performed for the F- + CH3I( v k = 0, 1) SN2 and proton-transfer reactions at nine different collision energies in the range of 1.0-35.3 kcal/mol using a full-dimensional high-level ab initio analytical potential energy surface with ground-state and excited CI stretching ( v3), CH3 rocking ( v6), CH3 umbrella ( v2), CH3 deformation ( v5), CH symmetric stretching ( v1), and CH asymmetric stretching ( v4) initial vibrational modes. Millions of trajectories provide statistically definitive mode-specific cross sections, opacity functions, scattering angle distributions, and product internal energy distributions. The excitation functions reveal slight vibrational SN2 inversion inhibition/enhancement at low/high collision energies ( Ecoll), whereas large decaying-with- Ecoll vibrational enhancement effects for the SN2 retention (double inversion) and proton-transfer channels. The most efficient vibrational enhancement is found by exciting the CI stretching (high Ecoll) for SN2 inversion and the CH stretching modes (low Ecoll) for double inversion and proton transfer. Mode-specific effects do not show up in the scattering angle distributions and do blue-shift the hot/cold SN2/proton-transfer product internal energies.
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Affiliation(s)
- Balázs Olasz
- Department of Physical Chemistry and Materials Science, Institute of Chemistry , University of Szeged , Rerrich Béla tér 1 , Szeged H-6720 , Hungary
| | - Gábor Czakó
- Department of Physical Chemistry and Materials Science, Institute of Chemistry , University of Szeged , Rerrich Béla tér 1 , Szeged H-6720 , Hungary
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33
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Coates G, Ward BJ, Bakewell C, White AJP, Crimmin MR. Reactions of Fluoroalkanes with Mg-Mg Bonds: Scope, sp 3 C-F/sp 2 C-F Coupling and Mechanism. Chemistry 2018; 24:16282-16286. [PMID: 30207410 PMCID: PMC6471154 DOI: 10.1002/chem.201804580] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2018] [Indexed: 01/19/2023]
Abstract
sp3C−F Bonds of fluoroalkanes (7 examples; 1°, 2° and 3°) undergo addition to a low‐valent Mg−Mg species generating reactive organomagnesium reagents. Further reactions with a series of electrophiles results in a net C−F to C−B, C−Si, C−Sn or C−C bond transformation (11 examples, diversity). The new reactivity has been exploited in an unprecedented one‐pot magnesium‐mediated coupling of sp3C−F and sp2C−F bonds. Calculations suggest that the sp3C−F bond activation step occurs by frontside nucleophilic attack of the Mg−Mg reagent on the fluoroalkane.
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Affiliation(s)
- Greg Coates
- Department of Chemistry, Imperial College London, South Kensington, London, SW7 2AZ, UK
| | - Bryan J Ward
- Department of Chemistry, Imperial College London, South Kensington, London, SW7 2AZ, UK
| | - Clare Bakewell
- Department of Chemistry, Imperial College London, South Kensington, London, SW7 2AZ, UK
| | - Andrew J P White
- Department of Chemistry, Imperial College London, South Kensington, London, SW7 2AZ, UK
| | - Mark R Crimmin
- Department of Chemistry, Imperial College London, South Kensington, London, SW7 2AZ, UK
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34
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Tasi DA, Fábián Z, Czakó G. Benchmark ab Initio Characterization of the Inversion and Retention Pathways of the OH– + CH3Y [Y = F, Cl, Br, I] SN2 Reactions. J Phys Chem A 2018; 122:5773-5780. [DOI: 10.1021/acs.jpca.8b04218] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Domonkos A. Tasi
- Department of Physical Chemistry and Materials Science, Institute of Chemistry, University of Szeged, Rerrich Béla tér 1, Szeged H-6720, Hungary
| | - Zita Fábián
- Department of Physical Chemistry and Materials Science, Institute of Chemistry, University of Szeged, Rerrich Béla tér 1, Szeged H-6720, Hungary
| | - Gábor Czakó
- Department of Physical Chemistry and Materials Science, Institute of Chemistry, University of Szeged, Rerrich Béla tér 1, Szeged H-6720, Hungary
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35
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Li Y, Wang D. Newly proposed proton-abstraction roundabout with backside attack mechanism for the S N2 reaction at the nitrogen center in F - + NH 2Cl. Phys Chem Chem Phys 2018; 20:12106-12111. [PMID: 29676410 DOI: 10.1039/c8cp01201f] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Abstract
Recent studies have improved our understanding of the mechanism and dynamics of the bimolecular nucleophilic substitution (SN2) reaction at the carbon center. Nonetheless, the SN2 reaction at the nitrogen center has received scarce attention and is less understood. Herein, we propose a new reaction mechanism for the SN2 reaction at the nitrogen center in the F- + NH2Cl reaction using ab initio molecular dynamics calculations. The newly proposed mechanism involves the rotation of NHCl with one proton of NH2Cl abstracted by the nucleophile, followed by the classical backside-attack process. The double-inversion mechanism revealed recently for the SN2 reaction at the carbon center is also observed for the title reaction at the nitrogen center. In contrast to the F- + CH3Cl reaction with a proton abstraction-induced first inversion transition state, the F- + NH2Cl reaction is a hydrogen bond-induced inversion. This newly proposed reaction mechanism opens a reaction channel to avoid the proton abstraction mechanism at low collision energy. The double-inversion mechanism of the title reaction with a negative first-inversion transition relative to the energy of the reactants is expected to have larger contribution to the reaction rate than the F- + CH3Cl reaction with a positive first-inversion transition state.
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Affiliation(s)
- Yongfang Li
- College of Physics and Electronics, Shandong Normal University, Jinan, Shandong 250014, China.
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36
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Győri T, Olasz B, Paragi G, Czakó G. Effects of the Level of Electronic Structure Theory on the Dynamics of the F - + CH 3I Reaction. J Phys Chem A 2018; 122:3353-3364. [PMID: 29546993 DOI: 10.1021/acs.jpca.8b00770] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Accuracy of the different levels of electronic structure theory is frequently studied for stationary-point properties; however, little is known about the effects of the electronic structure methods and basis sets on the dynamics of chemical reactions. Here we report such an investigation for the F- + CH3I SN2 and proton-transfer reactions by developing 20 different analytical potential energy surfaces (PESs) obtained at the HF/DZ, HF/TZ, HF-D3(BJ)/DZ, HF-D3(BJ)/TZ, MP2/DZ, MP2/TZ, MP2-F12/DZ, MP2-F12/TZ, CCSD/DZ, CCSD-F12b/DZ, CCSD(T)/DZ, CCSD(T)-F12b/DZ, OQVCCD(T)/DZ, B97-1/TZ, PBE0/TZ, PBE0-D3(BJ)/TZ, M06-2X/TZ, M06-2X-D3(0)/TZ, B2PLYP/TZ, and B2PLYP-D3(BJ)/TZ levels of theory, where DZ and TZ denote the aug-cc-pVDZ and aug-cc-pVTZ basis sets with a relativistic effective core potential and the corresponding bases for iodine. Millions of quasiclassical trajectories on these PESs reveal that (a) in the case of standard methods, increasing the basis from DZ to TZ decreases the SN2 cross sections by 20-30%; (b) the explicitly correlated F12 reactivity is converged with a DZ basis;
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Affiliation(s)
- Tibor Győri
- Department of Physical Chemistry and Materials Science, Institute of Chemistry , University of Szeged , Rerrich Béla tér 1 , Szeged H-6720 , Hungary
| | - Balázs Olasz
- Department of Physical Chemistry and Materials Science, Institute of Chemistry , University of Szeged , Rerrich Béla tér 1 , Szeged H-6720 , Hungary
| | - Gábor Paragi
- MTA-SZTE Biomimetic Systems Research Group , University of Szeged , Dóm tér 8 , Szeged H-6720 , Hungary
| | - Gábor Czakó
- Department of Physical Chemistry and Materials Science, Institute of Chemistry , University of Szeged , Rerrich Béla tér 1 , Szeged H-6720 , Hungary
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37
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Hajdu B, Czakó G. Benchmark ab Initio Characterization of the Complex Potential Energy Surfaces of the X - + NH 2Y [X, Y = F, Cl, Br, I] Reactions. J Phys Chem A 2018; 122:1886-1895. [PMID: 29360360 DOI: 10.1021/acs.jpca.7b11927] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
We report a comprehensive high-level explicitly correlated ab initio study on the X- + NH2Y [X,Y = F, Cl, Br, I] reactions characterizing the stationary points of the SN2 (Y- + NH2X) and proton-transfer (HX + NHY-) pathways as well as the reaction enthalpies of various endothermic additional product channels such as H- + NHXY, XY- + NH2, XY + NH2-, and XHY- + NH. Benchmark structures and harmonic vibrational frequencies are obtained at the CCSD(T)-F12b/aug-cc-pVTZ(-PP) level of theory, followed by CCSD(T)-F12b/aug-cc-pVnZ(-PP) [n = Q and 5] and core correlation energy computations. In the entrance and exit channels we find two equivalent hydrogen-bonded C1 minima, X-···HH'NY and X-···H'HNY connected by a Cs first-order saddle point, X-···H2NY, as well as a halogen-bonded front-side complex, X-···YNH2. SN2 reactions can proceed via back-side attack Walden inversion and front-side attack retention pathways characterized by first-order saddle points, submerged [X-NH2-Y]- and high-energy [H2NXY]-, respectively. Product-like stationary points below the HX + NHY- asymptotes are involved in the proton-transfer processes.
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Affiliation(s)
- Bálint Hajdu
- Department of Physical Chemistry and Materials Science, Institute of Chemistry, University of Szeged , Rerrich Béla tér 1, Szeged H-6720, Hungary
| | - Gábor Czakó
- Department of Physical Chemistry and Materials Science, Institute of Chemistry, University of Szeged , Rerrich Béla tér 1, Szeged H-6720, Hungary
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38
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Liu X, Zhao C, Yang L, Zhang J, Sun R. Indirect dynamics in S N2@N: insight into the influence of central atoms. Phys Chem Chem Phys 2018; 19:22691-22699. [PMID: 28816323 DOI: 10.1039/c7cp04199c] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Central atoms have a significant influence on the reaction kinetics and dynamics of nucleophilic substitution (SN2). Herein, atomistic dynamics of a prototype SN2@N reaction F- + NH2Cl is uncovered employing direct dynamics simulations that show strikingly distinct features from those determined for a SN2@C congener F- + CH3Cl. Indirect scattering is found to prevail, which proceeds predominantly through a hydrogen-bonded F--HNHCl complex in the reactant entrance channel. This unexpected finding of a pronounced contribution of indirect reaction dynamics, even at a high collision energy, is in strong contrast to a general evolution from indirect to direct dynamics with enhanced energy that characterizes SN2@C. This result suggests that the relative importance of different atomic-level mechanisms may depend essentially on the interaction potential of reactive encounters and the coupling between inter- and intramolecular modes of the pre-reaction complex. For F- + NH2Cl the proton transfer pathway is less competitive than SN2. A remarkable finding is that the more favorable energetics for NH2Cl proton transfer, as compared to that for CH3Cl, does not manifest itself in the reaction dynamics. The present work sheds light on the underlying reaction dynamics of SN2@N, which remain largely unclear compared to well-studied SN2@C.
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Affiliation(s)
- Xu Liu
- MIIT Key Laboratory of Critical Materials Technology for New Energy Conversion and Storage, School of Chemistry and Chemical Engineering, Harbin Institute of Technology, Harbin 150001, P. R. China.
| | - Chenyang Zhao
- MIIT Key Laboratory of Critical Materials Technology for New Energy Conversion and Storage, School of Chemistry and Chemical Engineering, Harbin Institute of Technology, Harbin 150001, P. R. China.
| | - Li Yang
- MIIT Key Laboratory of Critical Materials Technology for New Energy Conversion and Storage, School of Chemistry and Chemical Engineering, Harbin Institute of Technology, Harbin 150001, P. R. China.
| | - Jiaxu Zhang
- MIIT Key Laboratory of Critical Materials Technology for New Energy Conversion and Storage, School of Chemistry and Chemical Engineering, Harbin Institute of Technology, Harbin 150001, P. R. China.
| | - Rui Sun
- Department of Chemistry, University of Hawaii at Manoa, Honolulu, HI 96822-2275, USA
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Ma YT, Ma X, Li A, Guo H, Yang L, Zhang J, Hase WL. Potential energy surface stationary points and dynamics of the F - + CH 3I double inversion mechanism. Phys Chem Chem Phys 2018; 19:20127-20136. [PMID: 28726900 DOI: 10.1039/c7cp02998e] [Citation(s) in RCA: 27] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
Abstract
Direct dynamics simulations were performed to study the SN2 double inversion mechanism SN2-DI, with retention of configuration, for the F- + CH3I reaction. Previous simulations identified a transition state (TS) structure, i.e. TS0, for the SN2-DI mechanism, including a reaction path. However, intrinsic reaction coordinate (IRC) calculations from TS0 show it is a proton transfer (PT) TS connected to the F-HCH2I SN2 pre-reaction complex and the FHCH2I- proton transfer post-reaction complex. Inclusion of TS0 in the SN2-DI mechanism would thus involve non-IRC atomistic dynamics. Indeed, trajectories initiated at TS0, with random ensembles of energies as assumed by RRKM theory, preferentially form the SN2-DI products and ∼70% follow the proposed SN2-DI pathway from TS0 to the products. In addition, the Sudden Vector Projection (SVP) method was used to identify which CH3I vibrational mode excitations promote access to TS0 and the SN2-DI mechanism. Results of F- + CH3I simulations, with SVP specified mode excitations, are disappointing. With the CH3 deformations of CH3I excited, the SN2 single inversion mechanism is the dominant pathway. If the CH stretch modes are also excited, proton transfer dominates the reaction. SN2-DI occurs, but with a very small probability of ∼1%. The reasons behind these results are discussed.
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Affiliation(s)
- Yong-Tao Ma
- Department of Chemistry and Biochemistry, Texas Tech University, Lubbock, Texas 79409, USA.
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Pai SJ, Han SS. S E2 reaction in noncarbon system: Metal-halide catalysis for dehydrogenation of ammonia borane. Proc Natl Acad Sci U S A 2017; 114:13625-13630. [PMID: 29229814 PMCID: PMC5748185 DOI: 10.1073/pnas.1712137115] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023] Open
Abstract
An electrophilic substitution (SE) reaction of BN isosteres has been investigated for the dehydrogenation of ammonia borane (AB) by metal chlorides (MCl2) using various ab initio calculations. In contrast to the typical SE reaction occurring at the carbon atom, the nitrogen atom in AB serves as the reaction center for the SE reaction with the boron moiety as the leaving group when the MCl2 approaches the AB. The SE2 backside reaction is favored as a trigger step for the dehydrogenation of AB by the MCl2 The SE2 reaction is found for 3d-transition-metal chlorides (e.g., FeCl2, CoCl2, NiCl2, CuCl2, and ZnCl2), while PdCl2 leads to the dehydrogenation of AB by a direct B-H σ-bond activation, similar to most organometallic catalysts. Interestingly, the polymerization of AB promoted by MCl2 can be explained with the similar SE2 mechanism, and the dehydrogenation of the BN derivative 3-methyl-1,2-BN-cyclopentane (CBN) bearing a carbon backbone ring also follows the SE2 reaction. In particular, the experimental observation that the use of metal-chloride catalysis decreases the by-products obtained during the hydrogenation of AB can be explained by our mechanism involving the SE2 reaction. This work is helpful for the development of novel metal-halide catalysts for practical hydrogen storage materials, including the BN moiety.
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Affiliation(s)
- Sung Jin Pai
- Computational Science Research Center, Korea Institute of Science and Technology, Seongbuk-gu, Seoul 136-791, Republic of Korea
| | - Sang Soo Han
- Computational Science Research Center, Korea Institute of Science and Technology, Seongbuk-gu, Seoul 136-791, Republic of Korea
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41
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Carrascosa E, Meyer J, Michaelsen T, Stei M, Wester R. Conservation of direct dynamics in sterically hindered S N2/E2 reactions. Chem Sci 2017; 9:693-701. [PMID: 29629138 PMCID: PMC5869569 DOI: 10.1039/c7sc04415a] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2017] [Accepted: 11/09/2017] [Indexed: 11/21/2022] Open
Abstract
Nucleophilic substitution (SN2) and base-induced elimination (E2), two indispensable reactions in organic synthesis, are commonly assumed to proceed under stereospecific conditions. Understanding the way in which the reactants pre-orient in these reactions, that is its stereodynamics, is essential in order to achieve a detailed atomistic picture and control over such processes. Using crossed beam velocity map imaging, we study the effect of steric hindrance in reactions of Cl- and CN- with increasingly methylated alkyl iodides by monitoring the product ion energy and scattering angle. For both attacking anions the rebound mechanism, indicative of a direct SN2 pathway, is found to contribute to the reaction at high relative collision energies despite being increasingly hindered. An additional forward scattering mechanism, ascribed to a direct E2 reaction, also contributes at these energies. Inspection of the product energy distributions confirms the direct and fast character of both mechanisms as opposed to an indirect reaction mechanism which leads to statistical energy redistribution in the reaction complex. This work demonstrates that nonstatistical dynamics and energetics govern SN2 and E2 pathways even in sterically hindered exchange reaction systems.
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Affiliation(s)
- Eduardo Carrascosa
- Institut für Ionenphysik und Angewandte Physik , Universität Innsbruck , Technikerstraße 25 , 6020 Innsbruck , Austria . ; Tel: +43 512 507 52620
| | - Jennifer Meyer
- Institut für Ionenphysik und Angewandte Physik , Universität Innsbruck , Technikerstraße 25 , 6020 Innsbruck , Austria . ; Tel: +43 512 507 52620
| | - Tim Michaelsen
- Institut für Ionenphysik und Angewandte Physik , Universität Innsbruck , Technikerstraße 25 , 6020 Innsbruck , Austria . ; Tel: +43 512 507 52620
| | - Martin Stei
- Institut für Ionenphysik und Angewandte Physik , Universität Innsbruck , Technikerstraße 25 , 6020 Innsbruck , Austria . ; Tel: +43 512 507 52620
| | - Roland Wester
- Institut für Ionenphysik und Angewandte Physik , Universität Innsbruck , Technikerstraße 25 , 6020 Innsbruck , Austria . ; Tel: +43 512 507 52620
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Szabó I, Czakó G. Dynamics and Novel Mechanisms of S N2 Reactions on ab Initio Analytical Potential Energy Surfaces. J Phys Chem A 2017; 121:9005-9019. [PMID: 28985079 DOI: 10.1021/acs.jpca.7b08140] [Citation(s) in RCA: 49] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
We describe a novel theoretical approach to the bimolecular nucleophilic substitution (SN2) reactions that is based on analytical potential energy surfaces (PESs) obtained by fitting a few tens of thousands high-level ab initio energy points. These PESs allow computing millions of quasi-classical trajectories thereby providing unprecedented statistical accuracy for SN2 reactions, as well as performing high-dimensional quantum dynamics computations. We developed full-dimensional ab initio PESs for the F- + CH3Y [Y = F, Cl, I] systems, which describe the direct and indirect, complex-forming Walden-inversion, the frontside attack, and the new double-inversion pathways as well as the proton-transfer channels. Reaction dynamics simulations on the new PESs revealed (a) a novel double-inversion SN2 mechanism, (b) frontside complex formation,
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Affiliation(s)
- István Szabó
- Department of Physical Chemistry and Materials Science, Institute of Chemistry, University of Szeged , Rerrich Béla tér 1, Szeged H-6720, Hungary
| | - Gábor Czakó
- Department of Physical Chemistry and Materials Science, Institute of Chemistry, University of Szeged , Rerrich Béla tér 1, Szeged H-6720, Hungary
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Szabó I, Czakó G. Benchmark ab Initio Characterization of the Complex Potential Energy Surface of the Cl– + CH3I Reaction. J Phys Chem A 2017; 121:5748-5757. [DOI: 10.1021/acs.jpca.7b05503] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- István Szabó
- Department of Physical Chemistry
and Materials Science, Institute of Chemistry, University of Szeged, Rerrich Béla tér 1, Szeged H-6720, Hungary
| | - Gábor Czakó
- Department of Physical Chemistry
and Materials Science, Institute of Chemistry, University of Szeged, Rerrich Béla tér 1, Szeged H-6720, Hungary
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44
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Carrascosa E, Meyer J, Wester R. Imaging the dynamics of ion–molecule reactions. Chem Soc Rev 2017; 46:7498-7516. [DOI: 10.1039/c7cs00623c] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
A range of ion–molecule reactions have been studied in the last years using the crossed-beam ion imaging technique, from charge transfer and proton transfer to nucleophilic substitution and elimination.
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Affiliation(s)
- Eduardo Carrascosa
- Institut für Ionenphysik und Angewandte Physik
- Universität Innsbruck
- 6020 Innsbruck
- Austria
| | - Jennifer Meyer
- Institut für Ionenphysik und Angewandte Physik
- Universität Innsbruck
- 6020 Innsbruck
- Austria
| | - Roland Wester
- Institut für Ionenphysik und Angewandte Physik
- Universität Innsbruck
- 6020 Innsbruck
- Austria
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