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Liu X, Tian S, Guo W, Li H, Pang B, Wu Y. Competing C and N as Reactive Centers for Microsolvated Ambident Nucleophiles CN -(H 2O) n=0-3: A Theoretical Study of E2/S N2 Reactions with CH 3CH 2X (X = Cl, Br, I). J Phys Chem A 2024; 128:4651-4662. [PMID: 38819200 DOI: 10.1021/acs.jpca.4c01226] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/01/2024]
Abstract
As an ambident nucleophile, CN- has both C and N atoms that can act as the reactive center to facilitate substitution reactions. We investigate in detail the potential energy profiles of CN-(H2O)0-3 with CH3CH2X (X = Cl, Br, I) to explore the influence of solvent molecules on competition between the different nucleophilic atoms C and N involving the SN2 and E2 pathways. The energy barrier sequence for the transition states follows C@inv-SN2 < N@inv-SN2 < C@anti-E2 < N@anti-E2. When two different atoms act as nucleophilic atoms, the SN2 reaction is always preferred over the E2 reaction, and this preference increases with microsolvation. For the ambident nucleophiles CN-(H2O)0-3, C as the reactive center always has stronger nucleophilicity and basicity than N acting as the reactive center. Regarding the leaving group, the height of the energy barrier is positively correlated with the acidity of the CH3CH2X substrate for the E2 pathway and with X-heterolysis for the SN2 pathway. Furthermore, we found that in the gas phase, the energy barrier for different leaving group systems decreases gradually in the order Cl > Br > I, while in the SMD solution, the energy barrier and product energy increase slightly in the system from X = Cl to Br; this change may be due to the significantly weakened transition-state interaction for the X = Br system. Our activation strain, quantitative molecular orbital, and charge analyses reveal the physical mechanisms underlying the various computed trends. In addition, we also demonstrate the two points recently proposed by Vermeeren, P. . Chem. Eur. J. 2020, 26, 15538-15548.
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Affiliation(s)
- Xu Liu
- College of Chemistry, Liaoning University, Shenyang 110036, China
| | - Shiqi Tian
- College of Chemistry, Liaoning University, Shenyang 110036, China
| | - Wenyu Guo
- College of Chemistry, Liaoning University, Shenyang 110036, China
| | - Hui Li
- College of Chemistry, Liaoning University, Shenyang 110036, 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
| | - Yang Wu
- College of Chemistry, Liaoning University, Shenyang 110036, China
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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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Remmerswaal WA, de Jong T, van de Vrande KNA, Louwersheimer R, Verwaal T, Filippov DV, Codée JDC, Hansen T. Backside versus Frontside S N2 Reactions of Alkyl Triflates and Alcohols. Chemistry 2024; 30:e202400590. [PMID: 38385647 DOI: 10.1002/chem.202400590] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2024] [Accepted: 02/22/2024] [Indexed: 02/23/2024]
Abstract
Nucleophilic substitution reactions are elementary reactions in organic chemistry that are used in many synthetic routes. By quantum chemical methods, we have investigated the intrinsic competition between the backside SN2 (SN2-b) and frontside SN2 (SN2-f) pathways using a set of simple alkyl triflates as the electrophile in combination with a systematic series of phenols and partially fluorinated ethanol nucleophiles. It is revealed how and why the well-established mechanistic preference for the SN2-b pathway slowly erodes and can even be overruled by the unusual SN2-f substitution mechanism going from strong to weak alcohol nucleophiles. Activation strain analyses disclose that the SN2-b pathway is favored for strong alcohol nucleophiles because of the well-known intrinsically more efficient approach to the electrophile resulting in a more stabilizing nucleophile-electrophile interaction. In contrast, the preference of weaker alcohol nucleophiles shifts to the SN2-f pathway, benefiting from a stabilizing hydrogen bond interaction between the incoming alcohol and the leaving group. This hydrogen bond interaction is strengthened by the increased acidity of the weaker alcohol nucleophiles, thereby steering the mechanistic preference toward the frontside SN2 pathway.
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Affiliation(s)
- Wouter A Remmerswaal
- Leiden Institute of Chemistry, Leiden University, Einsteinweg 55, 2333 CC, Leiden, The, Netherlands
| | - Tjeerd de Jong
- Leiden Institute of Chemistry, Leiden University, Einsteinweg 55, 2333 CC, Leiden, The, Netherlands
| | - Koen N A van de Vrande
- Leiden Institute of Chemistry, Leiden University, Einsteinweg 55, 2333 CC, Leiden, The, Netherlands
| | - Rick Louwersheimer
- Leiden Institute of Chemistry, Leiden University, Einsteinweg 55, 2333 CC, Leiden, The, Netherlands
| | - Thomas Verwaal
- Leiden Institute of Chemistry, Leiden University, Einsteinweg 55, 2333 CC, Leiden, The, Netherlands
| | - Dmitri V Filippov
- Leiden Institute of Chemistry, Leiden University, Einsteinweg 55, 2333 CC, Leiden, The, Netherlands
| | - Jeroen D C Codée
- Leiden Institute of Chemistry, Leiden University, Einsteinweg 55, 2333 CC, Leiden, The, Netherlands
| | - Thomas Hansen
- Leiden Institute of Chemistry, Leiden University, Einsteinweg 55, 2333 CC, Leiden, The, Netherlands
- Department of Chemistry and Pharmaceutical Sciences, AIMMS, Vrije Universiteit Amsterdam, De Boelelaan 1108, 1081 HZ, Amsterdam, The, Netherlands
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Shen C, Zhang F, Sasaki T, Eerdun C, Hayashi M, Wang HW, Tominaga K, Mutailipu M, Pan S. Where do the Fluorine Atoms Go in Inorganic-Oxide Fluorinations? A Fluorooxoborate Illustration under Terahertz Light. Angew Chem Int Ed Engl 2024; 63:e202319121. [PMID: 38344870 DOI: 10.1002/anie.202319121] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2023] [Indexed: 03/01/2024]
Abstract
The substitution of fluorine atoms for oxygen atoms/hydroxyl groups has emerged as a promising strategy to enhance the physical and chemical properties of oxides/hydroxides in fluorine chemistry. However, distinguishing fluorine from oxygen/hydroxyl in the reaction products poses a significant challenge in existing characterization methods. In this study, we illustrate that terahertz (THz) spectroscopy provides a powerful tool for addressing this challenge. To this end, we investigated two fluorination reactions of boric acid, utilizing MHF2 (M=Na, C(NH2)3) as fluorine reagents. Through an interplay between THz spectroscopy and solid-state density functional theory, we have conclusively demonstrated that fluorine atoms exclusively bind with the sp3-boron but not with the sp2-boron in the reaction products of Na[B(OH)3][B3O3F2(OH)2] (NaBOFH) and [C(NH2)3]2B3O3F4OH (GBF2). Based on this evidence, we have proposed a reaction pathway for the fluorinations under investigation, a process previously hindered due to structural ambiguity. This work represents a step forward in gaining a deeper understanding of the precise structures and reaction mechanisms involved in the fluorination of oxides/hydroxides, illuminated by the insights provided by THz spectroscopy.
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Affiliation(s)
- Chunjie Shen
- Research Center for Crystal Materials, Xinjiang Technical Institute of Physics and Chemistry, Chinese Academy of Sciences, Urumqi, 830011, China
- Institution Center of Materials Science and Optoelectronics Engineering, University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Feng Zhang
- Research Center for Crystal Materials, Xinjiang Technical Institute of Physics and Chemistry, Chinese Academy of Sciences, Urumqi, 830011, China
- Institution Center of Materials Science and Optoelectronics Engineering, University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Tetsuo Sasaki
- Research Institute of Electronics, Shizuoka University, Hamamatsu, Shizuoka, 432-8011, Japan
| | - Chaolu Eerdun
- Department of Pharmaceutical Sciences, Inner Mongolia Medical University, Jinshan Economic & Technology Development District, Hohhot, Inner Mongolia, 010110, China
| | - Michitoshi Hayashi
- Center for Condensed Matter Sciences, National Taiwan University, 1 Roosevelt Rd., Sec. 4, Taipei, 10617, Taiwan
| | - Houng-Wei Wang
- Center for Condensed Matter Sciences, National Taiwan University, 1 Roosevelt Rd., Sec. 4, Taipei, 10617, Taiwan
| | - Keisuke Tominaga
- Molecular Photoscience Research Center, Kobe University, Nada, Kobe, 657-8501, Japan
| | - Miriding Mutailipu
- Research Center for Crystal Materials, Xinjiang Technical Institute of Physics and Chemistry, Chinese Academy of Sciences, Urumqi, 830011, China
- Institution Center of Materials Science and Optoelectronics Engineering, University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Shilie Pan
- Research Center for Crystal Materials, Xinjiang Technical Institute of Physics and Chemistry, Chinese Academy of Sciences, Urumqi, 830011, China
- Institution Center of Materials Science and Optoelectronics Engineering, University of Chinese Academy of Sciences, Beijing, 100049, China
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Dékány AÁ, Czakó G. Detailed quasiclassical dynamics of the F - + SiH 3Cl multi-channel reaction. Phys Chem Chem Phys 2024; 26:10008-10020. [PMID: 38482549 DOI: 10.1039/d4cp00048j] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/28/2024]
Abstract
We report a detailed quasiclassical trajectory study on the F- + SiH3Cl multi-channel reaction using a full-dimensional ab initio analytical potential energy surface. Reaction probabilities, cross sections, initial attack and scattering angle distributions as well as product relative translational, internal, vibrational, and rotational energy distributions are obtained in the collision energy range of 1-40 kcal mol-1 for the following channels: SiH3F + Cl-, SiH2Cl- + HF, SiH2F- + HCl, SiH2FCl + H-, SiH2 + FHCl-, and SiHFCl- + H2. All the channels are translationally cold indicating indirect mechanisms, except proton transfer (SiH2Cl- + HF), which shows mixed direct-indirect character. The angular distributions vary depending on collision energy and inversion/retention for SiH3F + Cl-. In the case of SiH2Cl- + HF front-side/back-side attack backward-forward/forward scattering preference is found at low/high collision energy. SiH2F- + HCl is formed with isotropic scattering and the preferred angle of attack is similar to the SiH3F + Cl- channel. SiH2FCl + H-/SiH2 + FHCl- favors back-side attack and isotropic/backward scattering, whereas SiHFCl- + H2 does not show significant angular preference.
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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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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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7
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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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8
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Giricz A, Czakó G, Papp D. Alternating Stereospecificity upon Central-Atom Change: Dynamics of the F - +PH 2 Cl S N 2 Reaction Compared to its C- and N-Centered Analogues. Chemistry 2023; 29:e202302113. [PMID: 37698297 DOI: 10.1002/chem.202302113] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2023] [Indexed: 09/13/2023]
Abstract
Central-atom effects on bimolecular nucleophilic substitution (SN 2) reactions are well-known in chemistry, however, the atomic-level SN 2 dynamics at phosphorous (P) centers has never been studied. We investigate the dynamics of the F- +PH2 Cl reaction with the quasi-classical trajectory method on a novel full-dimensional analytical potential energy surface fitted on high-level ab initio data. Our computations reveal intermediate dynamics compared to the F- +CH3 Cl and the F- +NH2 Cl SN 2 reactions: phosphorus as central atom leads to a more indirect SN 2 reaction with extensive complex-formation with respect to the carbon-centered one, however, the title reaction is more direct than its N-centered pair. Stereospecificity, characteristic at C-center, does not appear here either, due to the submerged front-side-attack retention path and the repeated entrance-channel inversional motion, whereas the multi-inversion mechanism discovered at nitrogen center is also undermined by the deep Walden-well. At low collision energies, 6 % of the PH2 F products form with retained configuration, mostly through complex-mediated mechanisms, while this ratio reaches 24 % at the highest energy due to the increasing dominance of the direct front-side mechanism and the smaller chance for hitting the deep Walden-inversion minimum. Our results suggest pronounced central-atom effects in SN 2 reactions, which can fundamentally change their (stereo)dynamics.
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Affiliation(s)
- Anett Giricz
- 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
| | - 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
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9
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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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Tasi DA, Michaelsen T, Wester R, Czakó G. Quasi-classical trajectory study of the OH - + CH 3I reaction: theory meets experiment. Phys Chem Chem Phys 2023; 25:4005-4014. [PMID: 36649119 DOI: 10.1039/d2cp05553h] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
Regarding OH- + CH3I, several studies have focused on the dynamics of the reaction. Here, high-level quasi-classical trajectory simulations are carried out at four different collision energies on our recently developed potential energy surface. In all, more than half a million trajectories are performed, and for the first time, the detailed quasi-classical trajectory results are compared with the reanalysed crossed-beam ion imaging experiments. Concerning the previously reported direct dynamics study of OH- + CH3I, a better agreement can be obtained between the revised experiment and our novel theoretical results. Furthermore, in the present work, the benchmark geometries, frequencies and relative energies of the stationary points are also determined for the OH- + CH3I proton-abstraction channel along with the earlier characterized SN2 channel.
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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, Rerrich Béla tér 1, Szeged H-6720, Hungary.
| | - Tim Michaelsen
- 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
| | - Gábor Czakó
- 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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11
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Oda K, Tsutsumi T, Keshavamurthy S, Furuya K, Armentrout PB, Taketsugu T. Dynamically Hidden Reaction Paths in the Reaction of CF 3+ + CO. ACS PHYSICAL CHEMISTRY AU 2022; 2:388-398. [PMID: 36193292 PMCID: PMC9524575 DOI: 10.1021/acsphyschemau.2c00012] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 12/03/2022]
Abstract
![]()
Reaction paths on
a potential energy surface are widely used in
quantum chemical studies of chemical reactions. The recently developed
global reaction route mapping (GRRM) strategy automatically constructs
a reaction route map, which provides a complete picture of the reaction.
Here, we thoroughly investigate the correspondence between the reaction
route map and the actual chemical reaction dynamics for the CF3+ + CO reaction studied by guided ion beam tandem
mass spectrometry (GIBMS). In our experiments, FCO+, CF2+, and CF+ product ions were observed,
whereas if the collision partner is N2, only CF2+ is observed. Interestingly, for reaction with CO, GRRM-predicted
reaction paths leading to the CF+ + F2CO product
channel are found at a barrier height of about 2.5 eV, whereas the
experimentally obtained threshold for CF+ formation was
7.48 ± 0.15 eV. In other words, the ion was not obviously observed
in the GIBMS experiment, unless a much higher collision energy than
the requisite energy threshold was provided. On-the-fly molecular
dynamics simulations revealed a mechanism that hides these reaction
paths, in which a non-statistical energy distribution at the first
collisionally reached transition state prevents the reaction from
proceeding along some reaction paths. Our results highlight the existence
of dynamically hidden reaction paths that may be inaccessible in experiments
at specific energies and hence the importance of reaction dynamics
in controlling the destinations of chemical reactions.
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Affiliation(s)
- Kohei Oda
- Graduate School of Chemical Sciences and Engineering, Hokkaido University, Sapporo 060-0810, Japan
| | - Takuro Tsutsumi
- Department of Chemistry, Faculty of Science, Hokkaido University, Sapporo 060-0810, Japan
| | - Srihari Keshavamurthy
- Department of Chemistry, Faculty of Science, Hokkaido University, Sapporo 060-0810, Japan
- Department of Chemistry, Indian Institute of Technology, Kanpur 208 016, India
| | - Kenji Furuya
- Faculty of Arts and Science, Kyushu University, Motooka, Fukuoka 819-0395, Japan
- Department of Molecular and Material Sciences, Kyushu University, Kasuga, Fukuoka 816-8580, Japan
- Department of Chemistry, University of Utah, Salt Lake City 84112, United States
| | - P. B. Armentrout
- Department of Chemistry, University of Utah, Salt Lake City 84112, United States
| | - Tetsuya Taketsugu
- Department of Chemistry, Faculty of Science, Hokkaido University, Sapporo 060-0810, Japan
- Institute for Chemical Reaction Design and Discovery (WPI-ICReDD), Hokkaido University, Sapporo 001-0021, Japan
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12
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Yu F. Origin of the Microsolvation Effect on the Central Barriers of S N2 Reactions. J Phys Chem A 2022; 126:4342-4348. [PMID: 35785958 DOI: 10.1021/acs.jpca.2c01677] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
We have quantitatively analyzed the microsolvation effect on the central barriers of microsolvated bimolecular nucleophilic substitution (SN2) reactions by means of a two-step energy decomposition procedure. According to the first energy decompositions, an obvious increase in the central barrier for a microsolvated SN2 reaction against its unsolvated counterpart can be mainly ascribed to the fact that the interaction between the solute and the conjunct solvent becomes less attractive from the reactant complex to the transition state. On the basis of the second energy decompositions with symmetry-adapted perturbation theory, this less attractive interaction in the transition state is primarily due to the interplay of the changes in the electrostatic, exchange, and induction components. However, the contribution of the change for the dispersion component is relatively small. A distinct linear correlation has also been observed between the changes of the total interaction energies and those of the corresponding electrostatic components for the microsolvated SN2 reactions studied in this work. Moreover, the two-step energy decomposition procedure employed in this work is expected to be extensively applied to the gas phase reactions mediated by molecules or clusters.
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Affiliation(s)
- Feng Yu
- Department of Physics, School of Freshmen, Xi'an Technological University, No. 4 Jinhua North Road, Xi'an, Shaanxi 710032, China
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Tasi DA, Czakó G. Unconventional S N2 retention pathways induced by complex formation: High-level dynamics investigation of the NH 2 - + CH 3I polyatomic reaction. J Chem Phys 2022; 156:184306. [PMID: 35568546 DOI: 10.1063/5.0091789] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Investigations on the dynamics of chemical reactions have been a hot topic for experimental and theoretical studies over the last few decades. Here, we carry out the first high-level dynamical characterization for the polyatom-polyatom reaction between NH2 - and CH3I. A global analytical potential energy surface is developed to describe the possible pathways with the quasi-classical trajectory method at several collision energies. In addition to SN2 and proton abstraction, a significant iodine abstraction is identified, leading to the CH3 + [NH2⋯I]- products. For SN2, our computations reveal an indirect character as well, promoting the formation of [CH3⋯NH2] complexes. Two novel dominant SN2 retention pathways are uncovered induced by the rotation of the CH3 fragment in these latter [CH3⋯NH2] complexes. Moreover, these uncommon routes turn out to be the most dominant retention paths for the NH2 - + CH3I SN2 reaction.
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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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Song K, Song H, Li J. Validating experiments for the reaction H 2 + NH 2- by dynamical calculations on an accurate full-dimensional potential energy surface. Phys Chem Chem Phys 2022; 24:10160-10167. [PMID: 35420091 DOI: 10.1039/d2cp00870j] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Ion-molecule reactions play key roles in the field of ion related chemistry. As a prototypical multi-channel ion-molecule reaction, the reaction H2 + NH2- → NH3 + H- has been studied for decades. In this work, we develop a new globally accurate potential energy surface (PES) for the title system based on hundreds of thousands of sampled points over a wide dynamically relevant region that covers long-range interacting configuration space. The permutational invariant polynomial-neural network (PIP-NN) method is used for fitting and the resulting total root mean squared error (RMSE) is extremely small, 0.026 kcal mol-1. Extensive dynamical and kinetic calculations are carried out on this PIP-NN PES. Impressively, a unique phenomenon of significant reactivity suppression by exciting the rotational mode of H2 is reported, supported by both the quasi-classical trajectory (QCT) and quantum dynamics (QD) calculations. Further analysis uncovers that exciting the H2 rotational mode would prevent the formation of the reactant complex and thus suppress the reactivity. The calculated rate coefficients for H2/D2 + NH2- agree well with the experimental results, which show an inverse temperature dependence from 50 to 300 K, consistent with the capture nature of this barrierless reaction. The significant kinetic isotope effect observed by experiments is well reproduced by the QCT computations as well.
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Affiliation(s)
- Kaisheng Song
- School of Chemistry and Chemical Engineering & Chongqing Key Laboratory of Theoretical and Computational Chemistry, Chongqing University, Chongqing 401331, P. R. China.
| | - Hongwei Song
- State Key Laboratory of Magnetic Resonance and Atomic and Molecular Physics, Wuhan Institute of Physics and Mathematics, Innovation Academy for Precision Measurement Science and Technology, Chinese Academy of Sciences, Wuhan 430071, China.
| | - Jun Li
- School of Chemistry and Chemical Engineering & Chongqing Key Laboratory of Theoretical and Computational Chemistry, Chongqing University, Chongqing 401331, P. R. China.
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15
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Ji X, Xie J. Proton transfer-induced competing product channels of microsolvated Y -(H 2O) n + CH 3I (Y = F, Cl, Br, I) reactions. Phys Chem Chem Phys 2022; 24:7539-7550. [PMID: 35289813 DOI: 10.1039/d1cp04873b] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The potential energy profiles of three proton transfer-involved product channels for the reactions of Y-(H2O)1,2 + CH3I (Y = F, Cl, Br, I) were characterized using the B97-1/ECP/d method. These three channels include the (1) PTCH3 product channel that transfers a proton from methyl to nucleophile, (2) HO--induced nucleophilic substitution (HO--SN2) product channel, and (3) oxide ion substitution (OIS) product channel that gives CH3O- and HY products. The reaction enthalpies and barrier heights follow the order OIS > PTCH3 > HO--SN2 > Y--SN2, and thus HO--SN2 can compete with the most favored Y--SN2 product channel under singly-/doubly-hydrated conditions, while the PTCH3 channel only occurs under high collision energy and the OIS channel is the least probable. All product channels share the same pre-reaction complex, Y-(H2O)n-CH3I, in the entrance of the potential energy profile, signifying the importance of the pre-reaction complex. For HO-/Y--SN2 channels, we considered front-side attack, back-side attack, and halogen-bonded complex mechanisms. Incremental hydration increases the barriers of both HO-/Y--SN2 channels as well as their barrier difference, implying that the HO--SN2 channel becomes less important when further hydrated. Varying the nucleophile Y- from F- to I- also increases the barrier heights and barrier difference, which correlates with the proton affinity of the nucleophiles. Energy decomposition analyses show that both the orbital interaction energy and structural deformation energy of the transition states determine the SN2 barrier change trend with incremental hydration and varying Y-. In brief, this work computes the comprehensive potential energy surfaces of the HO--SN2 and PTCH3 channels and shows how proton transfer affects the microsolvated Y-(H2O)1,2 + CH3I reaction by competing with the traditional Y--SN2 channel.
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Affiliation(s)
- Xiaoyan Ji
- Key Laboratory of Cluster Science of Ministry of Education, Beijing Key Laboratory of Photoelectronic/Electrophotonic Conversion Materials, School of Chemistry and Chemical Engineering, Beijing Institute of Technology, Beijing 100081, China.
| | - Jing Xie
- Key Laboratory of Cluster Science of Ministry of Education, Beijing Key Laboratory of Photoelectronic/Electrophotonic Conversion Materials, School of Chemistry and Chemical Engineering, Beijing Institute of Technology, Beijing 100081, China.
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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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Computational Studies of Coinage Metal Anion M - + CH 3X (X = F, Cl, Br, I) Reactions in Gas Phase. MOLECULES (BASEL, SWITZERLAND) 2022; 27:molecules27010307. [PMID: 35011542 PMCID: PMC8746851 DOI: 10.3390/molecules27010307] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/10/2021] [Revised: 12/28/2021] [Accepted: 12/29/2021] [Indexed: 12/03/2022]
Abstract
We characterized the stationary points along the nucleophilic substitution (SN2), oxidative insertion (OI), halogen abstraction (XA), and proton transfer (PT) product channels of M− + CH3X (M = Cu, Ag, Au; X = F, Cl, Br, I) reactions using the CCSD(T)/aug-cc-pVTZ level of theory. In general, the reaction energies follow the order of PT > XA > SN2 > OI. The OI channel that results in oxidative insertion complex [CH3–M–X]− is most exothermic, and can be formed through a front-side attack of M on the C-X bond via a high transition state OxTS or through a SN2-mediated halogen rearrangement path via a much lower transition state invTS. The order of OxTS > invTS is inverted when changing M− to Pd, a d10 metal, because the symmetry of their HOMO orbital is different. The back-side attack SN2 pathway proceeds via typical Walden-inversion transition state that connects to pre- and post-reaction complexes. For X = Cl/Br/I, the invSN2-TS’s are, in general, submerged. The shape of this M− + CH3X SN2 PES is flatter as compared to that of a main-group base like F− + CH3X, whose PES has a double-well shape. When X = Br/I, a linear halogen-bonded complex [CH3−X∙··M]− can be formed as an intermediate upon the front-side attachment of M on the halogen atom X, and it either dissociates to CH3 + MX− through halogen abstraction or bends the C-X-M angle to continue the back-side SN2 path. Natural bond orbital analysis shows a polar covalent M−X bond is formed within oxidative insertion complex [CH3–M–X]−, whereas a noncovalent M–X halogen-bond interaction exists for the [CH3–X∙··M]− complex. This work explores competing channels of the M− + CH3X reaction in the gas phase and the potential energy surface is useful in understanding the dynamic behavior of the title and analogous reactions.
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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
![]()
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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Tasi DA, Czakó G. Uncovering an oxide ion substitution for the OH - + CH 3F reaction. Chem Sci 2021; 12:14369-14375. [PMID: 34880987 PMCID: PMC8580036 DOI: 10.1039/d1sc03834f] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2021] [Accepted: 10/13/2021] [Indexed: 11/21/2022] Open
Abstract
Theoretical investigations on chemical reactions allow us to understand the dynamics of the possible pathways and identify new unexpected routes. Here, we develop a global analytical potential energy surface (PES) for the OH− + CH3F reaction in order to perform high-level dynamics simulations. Besides bimolecular nucleophilic substitution (SN2) and proton abstraction, our quasi-classical trajectory computations reveal a novel oxide ion substitution leading to the HF + CH3O− products. This exothermic reaction pathway occurs via the CH3OH⋯F− deep potential well of the SN2 product channel as a result of a proton abstraction from the hydroxyl group by the fluoride ion. The present detailed dynamics study of the OH− + CH3F reaction focusing on the surprising oxide ion substitution demonstrates how incomplete our knowledge is of fundamental chemical reactions. Reaction dynamics simulations on a high-level ab initio analytical potential energy surface reveal a novel oxide ion substitution channel for the OH− + CH3F reaction.![]()
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Affiliation(s)
- Domonkos A Tasi
- MTA-SZTE Lendület Computational Reaction Dynamics Research Group, Interdisciplinary Excellence Centre, 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, 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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Kilaj A, Wang J, Straňák P, Schwilk M, Rivero U, Xu L, von Lilienfeld OA, Küpper J, Willitsch S. Conformer-specific polar cycloaddition of dibromobutadiene with trapped propene ions. Nat Commun 2021; 12:6047. [PMID: 34663806 PMCID: PMC8523519 DOI: 10.1038/s41467-021-26309-5] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2021] [Accepted: 09/24/2021] [Indexed: 11/16/2022] Open
Abstract
Diels–Alder cycloadditions are efficient routes for the synthesis of cyclic organic compounds. There has been a long-standing discussion whether these reactions proceed via stepwise or concerted mechanisms. Here, we adopt an experimental approach to explore the mechanism of the model polar cycloaddition of 2,3-dibromo-1,3-butadiene with propene ions by probing its conformational specificities in the entrance channel under single-collision conditions in the gas phase. Combining a conformationally controlled molecular beam with trapped ions, we find that both conformers of the diene, gauche and s-trans, are reactive with capture-limited reaction rates. Aided by quantum-chemical and quantum-capture calculations, this finding is rationalised by a simultaneous competition of concerted and stepwise reaction pathways, revealing an interesting mechanistic borderline case. Identifying a concerted or stepwise mechanism in Diels–Alder reactions is experimentally challenging. Here the authors demonstrate the coexistence of both mechanisms in the reaction of 2,3-dibromobuta-1,3-diene with propene ions, using a conformationally controlled molecular beam reacting with trapped ions and ab initio computations
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Affiliation(s)
- Ardita Kilaj
- Department of Chemistry, University of Basel, Klingelbergstrasse 80, 4056, Basel, Switzerland
| | - Jia Wang
- Center for Free-Electron Laser Science, Deutsches Elektronen-Synchrotron DESY, Notkestrasse 85, 22607, Hamburg, Germany
| | - Patrik Straňák
- Department of Chemistry, University of Basel, Klingelbergstrasse 80, 4056, Basel, Switzerland
| | - Max Schwilk
- Department of Chemistry, University of Basel, Klingelbergstrasse 80, 4056, Basel, Switzerland.,Faculty of Physics, University of Vienna, 1090, Vienna, Austria
| | - Uxía Rivero
- Department of Chemistry, University of Basel, Klingelbergstrasse 80, 4056, Basel, Switzerland
| | - Lei Xu
- Department of Chemistry, University of Basel, Klingelbergstrasse 80, 4056, Basel, Switzerland
| | - O Anatole von Lilienfeld
- Department of Chemistry, University of Basel, Klingelbergstrasse 80, 4056, Basel, Switzerland.,Faculty of Physics, University of Vienna, 1090, Vienna, Austria
| | - Jochen Küpper
- Center for Free-Electron Laser Science, Deutsches Elektronen-Synchrotron DESY, Notkestrasse 85, 22607, Hamburg, Germany. .,Department of Physics, Universität Hamburg, Luruper Chaussee 149, 22761, Hamburg, Germany. .,Department of Chemistry, Universität Hamburg, Martin-Luther-King-Platz 6, 20146, Hamburg, Germany. .,Center for Ultrafast Imaging, Universität Hamburg, Luruper Chaussee 149, 22761, Hamburg, Germany.
| | - Stefan Willitsch
- Department of Chemistry, University of Basel, Klingelbergstrasse 80, 4056, Basel, Switzerland.
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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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