Simulation studies of the Cl{sup -}+ CH{sub 3}I S{sub N}2 nucleophilic substitution reaction: Comparison with ion imaging experiments
Abstract
In the previous work of Mikosch et al.[Science 319, 183 (2008)], ion imaging experiments were used to study the Cl{sup -}+ CH{sub 3}I {yields} ClCH{sub 3}+ I{sup -} reaction at collision energies E{sub rel} of 0.39, 0.76, 1.07, and 1.9 eV. For the work reported here MP2(fc)/ECP/d direct dynamics simulations were performed to obtain an atomistic understanding of the experiments. There is good agreement with the experimental product energy and scattering angle distributions for the highest three E{sub rel}, and at these energies 80% or more of the reaction is direct, primarily occurring by a rebound mechanism with backward scattering. At 0.76 eV there is a small indirect component, with isotropic scattering, involving formation of the pre- and post-reaction complexes. All of the reaction is direct at 1.07 eV. Increasing E{sub rel} to 1.9 eV opens up a new indirect pathway, the roundabout mechanism. The product energy is primarily partitioned into relative translation for the direct reactions, but to CH{sub 3}Cl internal energy for the indirect reactions. The roundabout mechanism transfers substantial energy to CH{sub 3}Cl rotation. At E{sub rel}= 0.39 eV both the experimental product energy partitioning and scattering are statistical, suggesting the reaction is primarily indirect with formationmore »
- Authors:
-
- Beijing National Laboratory for Molecular Sciences, State Key Laboratory of Molecular Reaction Dynamics, Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190 (China)
- Department of Chemistry and Biochemistry, Texas Tech University, Lubbock, Texas 79409-1061 (United States)
- National Research Council of Canada, Steacie Institute for Molecular Sciences, 100 Sussex Drive, Ottawa, Ontario K1AOR6 (Canada)
- Institut fur Ionenphysik und Angewandte Physik, Universitaet Innsbruck, Technikerstrasse 25/3, A-6020 Innsbruck (Austria)
- Publication Date:
- OSTI Identifier:
- 22105432
- Resource Type:
- Journal Article
- Journal Name:
- Journal of Chemical Physics
- Additional Journal Information:
- Journal Volume: 138; Journal Issue: 11; Other Information: (c) 2013 American Institute of Physics; Country of input: International Atomic Energy Agency (IAEA); Journal ID: ISSN 0021-9606
- Country of Publication:
- United States
- Language:
- English
- Subject:
- 74 ATOMIC AND MOLECULAR PHYSICS; 37 INORGANIC, ORGANIC, PHYSICAL AND ANALYTICAL CHEMISTRY; CHLORINE IONS; COMPARATIVE EVALUATIONS; COMPLEXES; DIRECT REACTIONS; DISTRIBUTION; EV RANGE; IODINE IONS; ION-MOLECULE COLLISIONS; METHYL CHLORIDE; METHYL IODIDE; PHASE SPACE; REACTION KINETICS; ROTATIONAL STATES; SCATTERING; SIMULATION
Citation Formats
Jiaxu, Zhang, Lourderaj, Upakarasamy, Rui, Sun, Hase, William L., Mikosch, Jochen, and Wester, Roland. Simulation studies of the Cl{sup -}+ CH{sub 3}I S{sub N}2 nucleophilic substitution reaction: Comparison with ion imaging experiments. United States: N. p., 2013.
Web. doi:10.1063/1.4795495.
Jiaxu, Zhang, Lourderaj, Upakarasamy, Rui, Sun, Hase, William L., Mikosch, Jochen, & Wester, Roland. Simulation studies of the Cl{sup -}+ CH{sub 3}I S{sub N}2 nucleophilic substitution reaction: Comparison with ion imaging experiments. United States. https://doi.org/10.1063/1.4795495
Jiaxu, Zhang, Lourderaj, Upakarasamy, Rui, Sun, Hase, William L., Mikosch, Jochen, and Wester, Roland. 2013.
"Simulation studies of the Cl{sup -}+ CH{sub 3}I S{sub N}2 nucleophilic substitution reaction: Comparison with ion imaging experiments". United States. https://doi.org/10.1063/1.4795495.
@article{osti_22105432,
title = {Simulation studies of the Cl{sup -}+ CH{sub 3}I S{sub N}2 nucleophilic substitution reaction: Comparison with ion imaging experiments},
author = {Jiaxu, Zhang and Lourderaj, Upakarasamy and Rui, Sun and Hase, William L. and Mikosch, Jochen and Wester, Roland},
abstractNote = {In the previous work of Mikosch et al.[Science 319, 183 (2008)], ion imaging experiments were used to study the Cl{sup -}+ CH{sub 3}I {yields} ClCH{sub 3}+ I{sup -} reaction at collision energies E{sub rel} of 0.39, 0.76, 1.07, and 1.9 eV. For the work reported here MP2(fc)/ECP/d direct dynamics simulations were performed to obtain an atomistic understanding of the experiments. There is good agreement with the experimental product energy and scattering angle distributions for the highest three E{sub rel}, and at these energies 80% or more of the reaction is direct, primarily occurring by a rebound mechanism with backward scattering. At 0.76 eV there is a small indirect component, with isotropic scattering, involving formation of the pre- and post-reaction complexes. All of the reaction is direct at 1.07 eV. Increasing E{sub rel} to 1.9 eV opens up a new indirect pathway, the roundabout mechanism. The product energy is primarily partitioned into relative translation for the direct reactions, but to CH{sub 3}Cl internal energy for the indirect reactions. The roundabout mechanism transfers substantial energy to CH{sub 3}Cl rotation. At E{sub rel}= 0.39 eV both the experimental product energy partitioning and scattering are statistical, suggesting the reaction is primarily indirect with formation of the pre- and post-reaction complexes. However, neither MP2 nor BhandH/ECP/d simulations agree with experiment and, instead, give reaction dominated by direct processes as found for the higher collision energies. Decreasing the simulation E{sub rel} to 0.20 eV results in product energy partitioning and scattering which agree with the 0.39 eV experiment. The sharp transition from a dominant direct to indirect reaction as E{sub rel} is lowered from 0.39 to 0.20 eV is striking. The lack of agreement between the simulations and experiment for E{sub rel}= 0.39 eV may result from a distribution of collision energies in the experiment and/or a shortcoming in both the MP2 and BhandH simulations. Increasing the reactant rotational temperature from 75 to 300 K for the 1.9 eV collisions, results in more rotational energy in the CH{sub 3}Cl product and a larger fraction of roundabout trajectories. Even though a ClCH{sub 3}-I{sup -} post-reaction complex is not formed and the mechanistic dynamics are not statistical, the roundabout mechanism gives product energy partitioning in approximate agreement with phase space theory.},
doi = {10.1063/1.4795495},
url = {https://www.osti.gov/biblio/22105432},
journal = {Journal of Chemical Physics},
issn = {0021-9606},
number = 11,
volume = 138,
place = {United States},
year = {Thu Mar 21 00:00:00 EDT 2013},
month = {Thu Mar 21 00:00:00 EDT 2013}
}