1
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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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2
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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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3
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Qin J, Liu Y, Li J. Quantitative Dynamics of Paradigmatic SN2 reaction OH− + CH3F on Accurate Full-Dimensional Potential Energy Surface. J Chem Phys 2022; 157:124301. [DOI: 10.1063/5.0112228] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
The bimolecular reaction between OH− and CH3F is not just a prototypical SN2 process but also has three other product channels. Here, we develop an accurate full-dimensional potential energy surface (PES) based on 191 193 points calculated at the level CCSD(T)-F12a/aug-cc-pVTZ. A detailed dynamics and mechanism analysis were carried out on this PES by using the quasi-classical trajectory approach. It is verified that the trajectories do not follow the minimum energy path (MEP) but directly dissociate to F− and CH3OH. In addition, a new transition state for proton exchange and a new product complex CH2F−‧‧‧H2O for proton abstraction were discovered. The trajectories avoid the transition state or this complex, instead dissociate to H2O and CH2F− directly through the ridge regions of the MEP before the transition state. These non-MEP dynamics become more pronounced at high collision energies. Detailed dynamics simulations provide new insights into the atomic-level mechanisms of the title reaction thanks to the new chemically accurate PES with the aid of the machine learning.
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Affiliation(s)
- Jie Qin
- Chemistry and Chemical Engineering, Chongqing University Department of Chemical Engineering, China
| | | | - Jun Li
- School of Chemistry and Chemical Engineering, Chongqing University, China
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4
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Meng F, Li Y, Wang D. Predicting atomic-level reaction mechanisms for S N2 reactions via machine learning. J Chem Phys 2021; 155:224111. [PMID: 34911303 DOI: 10.1063/5.0074422] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Abstract
Identifying atomic-level reaction mechanisms is an essential step in chemistry. In this study, we develop a joint-voting model based on three parallel machine-learning algorithms to predict atomic-level and dynamical mechanisms trained with 1700 trajectories. Three predictive experiments are carried out with the training trajectories divided into ten, seven, and five classes. The results indicate that, as the number of trajectories in each class increases from the ten- to five-class model, the five-class model converges the fastest and the prediction success rate increases. The number of trajectories in each experiment to get the predictive models converged is 100, 100, and 70, respectively. The prediction accuracy increases from 88.3% for the ten-class experiment, to 91.0% for the seven-class, and to 92.0% for the five-class. Our study demonstrates that machine learning can also be used to predict elementary dynamical processes of structural evolution along time, that is, atomic-level reaction mechanisms.
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Affiliation(s)
- Fanbin Meng
- School of Medical Information Engineering, Jining Medical University, Jining 272067, Shandong, China
| | - Yan Li
- College of Physics and Electronics, Shandong Normal University, Jinan 250014, Shandong, China
| | - Dunyou Wang
- College of Physics and Electronics, Shandong Normal University, Jinan 250014, Shandong, China
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5
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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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6
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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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7
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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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8
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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
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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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9
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Li J, Zhao B, Xie D, Guo H. Advances and New Challenges to Bimolecular Reaction Dynamics Theory. J Phys Chem Lett 2020; 11:8844-8860. [PMID: 32970441 DOI: 10.1021/acs.jpclett.0c02501] [Citation(s) in RCA: 32] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
Dynamics of bimolecular reactions in the gas phase are of foundational importance in combustion, atmospheric chemistry, interstellar chemistry, and plasma chemistry. These collision-induced chemical transformations are a sensitive probe of the underlying potential energy surface(s). Despite tremendous progress in past decades, our understanding is still not complete. In this Perspective, we survey the recent advances in theoretical characterization of bimolecular reaction dynamics, stimulated by new experimental observations, and identify key new challenges.
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Affiliation(s)
- Jun Li
- School of Chemistry and Chemical Engineering & Chongqing Key Laboratory of Theoretical and Computational Chemistry, Chongqing University, Chongqing 401331, China
| | - Bin Zhao
- Theoretische Chemie, Fakultät für Chemie, Universität Bielefeld, Universitätsstraße 25, D-33615 Bielefeld, Germany
| | - Daiqian Xie
- Institute of Theoretical and Computational Chemistry, School of Chemistry and Chemical Engineering, Nanjing University, Nanjing 210023, China
| | - Hua Guo
- Department of Chemistry and Chemical Biology, University of New Mexico, Albuquerque, New Mexico 87131, United States
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10
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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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11
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Li Y, Li Y, Wang D. The importance of the composite mechanisms with two transition states in the F - + NH 2I S N2 reaction. Phys Chem Chem Phys 2020; 22:12929-12938. [PMID: 32453309 DOI: 10.1039/d0cp01942a] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The dynamics of the bimolecular nucleophilic substitution (SN2) reactions at nitrogen are less understood than those of their corresponding reactions at carbon. In this paper, we report an ab initio molecular dynamics approach to investigate the reaction mechanisms of the F- + NH2I SN2 reaction at nitrogen. We found not only the one-transition-state mechanisms, but also the composite mechanisms with two and three transition states. For the two-transition-state mechanisms, the double inversion mechanism and the proton-abstraction roundabout followed by the backside-attack reaction mechanism have been reported before; but we discovered that there is also a new, front-side attack followed by the backside-attack Walden-inversion mechanism. Furthermore, a composite mechanism with three transition states also shows up in the reactive trajectories. Our results show that, as the collision energy increases, the SN2 reactivity decreases, and the proton-abstraction reactivity increases. The two-transition-state mechanisms, especially the double-inversion mechanism, make the largest contribution to the SN2 reactivity, followed then by the one-transition-state mechanisms, with the three-transition-state mechanism contributing the least. The potential energy profiles of the reaction mechanisms are characterized at the CCSD(T)/aug-cc-pVTZ(PP) level of theory. The analysis on stationary points shows that the proton-abstraction inversion transition state is ∼12.4 kcal mol-1 lower than the Walden-inversion transition state in contrast to the corresponding reaction at carbon F- + CH3I, in which the former is ∼26.1 kcal mol-1 higher than the latter. This might explain why the composite mechanism of the double inversion mechanism contributes the most to the SN2 reactivity in the F- + NH2I reaction.
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Affiliation(s)
- Yan Li
- College of Physics and Electronics, Shandong Normal University, Jinan 250014, Shandong, China.
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12
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Abstract
Nonstatistical dynamics is important for many chemical reactions. The Rice-Ramsperger-Kassel-Marcus (RRKM) theory of unimolecular kinetics assumes a reactant molecule maintains a statistical microcanonical ensemble of vibrational states during its dissociation so that its unimolecular dynamics are time independent. Such dynamics results when the reactant's atomic motion is chaotic or irregular. Intrinsic non-RRKM dynamics occurs when part of the reactant's phase space consists of quasiperiodic/regular motion and a bottleneck exists, so that the unimolecular rate constant is time dependent. Nonrandom excitation of a molecule may result in short-time apparent non-RRKM dynamics. For rotational activation, the 2J + 1 K levels for a particular J may be highly mixed, making K an active degree of freedom, or K may be a good quantum number and an adiabatic degree of freedom. Nonstatistical dynamics is often important for bimolecular reactions and their intermediates and for product-energy partitioning of bimolecular and unimolecular reactions. Post–transition state dynamics is often highly complex and nonstatistical.
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Affiliation(s)
- Bhumika Jayee
- Department of Chemistry and Biochemistry, Texas Tech University, Lubbock, Texas 79409, USA
| | - William L. Hase
- Department of Chemistry and Biochemistry, Texas Tech University, Lubbock, Texas 79409, USA
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13
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Yao Y, Lakshmanan S, Pratihar S, Hase WL. Direct Dynamics Simulations of the Unimolecular Decomposition of the Randomly Excited 1CH 2O 2 Criegee Intermediate. Comparison with 3CH 2 + 3O 2 Reaction Dynamics. J Phys Chem A 2020; 124:1821-1828. [DOI: 10.1021/acs.jpca.9b11513] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Affiliation(s)
- Yuxuan Yao
- Department of Chemistry and Biochemistry, Texas Tech University, Lubbock, Texas 79409, United States
| | - Sandhiya Lakshmanan
- Department of Chemistry and Biochemistry, Texas Tech University, Lubbock, Texas 79409, United States
- CSIR - National Institute of Science, Technology and Development Studies, New Delhi 110060, India
| | - Subha Pratihar
- Department of Chemistry and Biochemistry, Texas Tech University, Lubbock, Texas 79409, United States
| | - William L. Hase
- Department of Chemistry and Biochemistry, Texas Tech University, Lubbock, Texas 79409, United States
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14
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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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15
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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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16
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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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17
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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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18
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Nucleophilic substitution vs elimination reaction of bisulfide ions with substituted methanes: exploration of chiral selectivity by stereodirectional first-principles dynamics and transition state theory. J Mol Model 2019; 25:227. [PMID: 31317347 DOI: 10.1007/s00894-019-4126-0] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2019] [Accepted: 07/07/2019] [Indexed: 10/26/2022]
Abstract
Control of molecular orientation is emerging as crucial for the characterization of the stereodynamics of kinetics processes beyond structural stereochemistry. The special role played in chiral discrimination phenomena has been particularly emphasized by Aquilanti and collaborators after their extensive probes of experimental control of molecular alignment and orientation. In this work, the manifestation of the Aquilanti mechanism has been demonstrated for the first time in first-principles molecular dynamics simulations: stationary points characterized on potential energy surfaces have been calculated for the study of chemical reactions occurring between the bisulfide anion HS- and oriented prototypical chiral molecules CHFXY (where X = CH3 or CN and Y = Cl or I). The important reaction channels are those corresponding to bimolecular nucleophilic substitution (SN2) and to bimolecular elimination (E2): their relative role has been assessed and alternative pathways due to the mirror forms of the oriented chiral molecule are revealed by the different reactivity of the two enantiomers of CHFCNI in SN2 reaction.
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19
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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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20
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Olasz B, Czakó G. High-Level-Optimized Stationary Points for the F -(H 2O) + CH 3I System: Proposing a New Water-Induced Double-Inversion Pathway. J Phys Chem A 2019; 123:454-462. [PMID: 30571112 DOI: 10.1021/acs.jpca.8b10630] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
We report 29 stationary points for the F-(H2O) + CH3I reaction obtained by using the high-level explicitly correlated CCSD(T)-F12b method with the aug-cc-pVDZ basis set for the determination of the benchmark structures and frequencies and the aug-cc-pVQZ basis for energy computations. The stationary points characterize the monohydrated F-- and OH--induced Walden-inversion pathways and, for the first time, the front-side attack and F--induced double-inversion mechanisms leading to CH3F with retention as well as the novel H2O-induced double-inversion retention pathway producing CH3OH. Hydration effectively increases the relative energies of the stationary points, but the monohydrated inversion pathways are still barrierless, whereas the front-side attack and double-inversion barrier heights are around 30 and 20 kcal/mol, respectively.
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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
| | - 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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21
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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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22
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Stei M, Carrascosa E, Dörfler A, Meyer J, Olasz B, Czakó G, Li A, Guo H, Wester R. Stretching vibration is a spectator in nucleophilic substitution. SCIENCE ADVANCES 2018; 4:eaas9544. [PMID: 29984305 PMCID: PMC6035035 DOI: 10.1126/sciadv.aas9544] [Citation(s) in RCA: 32] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/09/2018] [Accepted: 05/22/2018] [Indexed: 06/08/2023]
Abstract
How chemical reactions are influenced by reactant vibrational excitation is a long-standing question at the core of chemical reaction dynamics. In reactions of polyatomic molecules, where the Polanyi rules are not directly applicable, certain vibrational modes can act as spectators. In nucleophilic substitution reactions, CH stretching vibrations have been considered to be such spectators. While this picture has been challenged by some theoretical studies, experimental insight has been lacking. We show that the nucleophilic substitution reaction of F- with CH3I is minimally influenced by an excitation of the symmetric CH stretching vibration. This contrasts with the strong vibrational enhancement of the proton transfer reaction measured in parallel. The spectator behavior of the stretching mode is supported by both quasi-classical trajectory simulations and the Sudden Vector Projection model.
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Affiliation(s)
- Martin Stei
- Institut für Ionenphysik und Angewandte Physik, Universität Innsbruck, Technikerstraße 25/3, 6020 Innsbruck, Austria
| | - Eduardo Carrascosa
- Institut für Ionenphysik und Angewandte Physik, Universität Innsbruck, Technikerstraße 25/3, 6020 Innsbruck, Austria
| | - Alexander Dörfler
- Institut für Ionenphysik und Angewandte Physik, Universität Innsbruck, Technikerstraße 25/3, 6020 Innsbruck, Austria
| | - Jennifer Meyer
- Institut für Ionenphysik und Angewandte Physik, Universität Innsbruck, Technikerstraße 25/3, 6020 Innsbruck, Austria
| | - Balázs Olasz
- Department of Physical Chemistry and Materials Science, University of Szeged, Rerrich Béla tér 1, Szeged H-6720, Hungary
| | - Gábor Czakó
- Department of Physical Chemistry and Materials Science, University of Szeged, Rerrich Béla tér 1, Szeged H-6720, Hungary
| | - Anyang Li
- Key Laboratory of Synthetic and Natural Functional Molecule Chemistry, Ministry of Education, College of Chemistry and Materials Science, Northwest University, 710127 Xian, P. R. China
| | - Hua Guo
- Department of Chemistry and Chemical Biology, University of New Mexico, Albuquerque, NM 87131, USA
| | - Roland Wester
- Institut für Ionenphysik und Angewandte Physik, Universität Innsbruck, Technikerstraße 25/3, 6020 Innsbruck, Austria
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23
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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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24
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Hamlin TA, Swart M, Bickelhaupt FM. Nucleophilic Substitution (S N 2): Dependence on Nucleophile, Leaving Group, Central Atom, Substituents, and Solvent. Chemphyschem 2018; 19:1315-1330. [PMID: 29542853 PMCID: PMC6001448 DOI: 10.1002/cphc.201701363] [Citation(s) in RCA: 118] [Impact Index Per Article: 19.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2017] [Indexed: 11/12/2022]
Abstract
The reaction potential energy surface (PES), and thus the mechanism of bimolecular nucleophilic substitution (SN 2), depends profoundly on the nature of the nucleophile and leaving group, but also on the central, electrophilic atom, its substituents, as well as on the medium in which the reaction takes place. Here, we provide an overview of recent studies and demonstrate how changes in any one of the aforementioned factors affect the SN 2 mechanism. One of the most striking effects is the transition from a double-well to a single-well PES when the central atom is changed from a second-period (e. g. carbon) to a higher-period element (e.g, silicon, germanium). Variations in nucleophilicity, leaving group ability, and bulky substituents around a second-row element central atom can then be exploited to change the single-well PES back into a double-well. Reversely, these variations can also be used to produce a single-well PES for second-period elements, for example, a stable pentavalent carbon species.
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Affiliation(s)
- Trevor A. Hamlin
- Department of Theoretical Chemistry andAmsterdam Center for Multiscale Modeling (ACMM)Vrije Universiteit AmsterdamDe Boelelaan 10831081 HVAmsterdamThe Netherlands
| | - Marcel Swart
- Department of Theoretical Chemistry andAmsterdam Center for Multiscale Modeling (ACMM)Vrije Universiteit AmsterdamDe Boelelaan 10831081 HVAmsterdamThe Netherlands
- Institut de Química Computacional I Catàlisi and Department de QuímicaUniversitat de Girona17003GironaSpain
- ICREAPg. Lluís Companys 2308010BarcelonaSpain
| | - F. Matthias Bickelhaupt
- Department of Theoretical Chemistry andAmsterdam Center for Multiscale Modeling (ACMM)Vrije Universiteit AmsterdamDe Boelelaan 10831081 HVAmsterdamThe Netherlands
- Institute of Molecules and Materials (IMM)Radboud UniversityHeyendaalseweg 1356525 AJNijmegenThe Netherlands
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25
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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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26
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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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27
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Krotos L, Czakó G. Does the Cl + CH4 → H + CH3Cl Reaction Proceed via Walden Inversion? J Phys Chem A 2017; 121:9415-9420. [DOI: 10.1021/acs.jpca.7b10226] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- László Krotos
- 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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28
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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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