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Article: Steric, quantum, and electrostatic effects on SN2 reaction barriers in gas phase

TitleSteric, quantum, and electrostatic effects on SN2 reaction barriers in gas phase
Authors
Issue Date2010
PublisherAmerican Chemical Society. The Journal's web site is located at http://pubs.acs.org/jpca
Citation
Journal Of Physical Chemistry A, 2010, v. 114 n. 18, p. 5913-5918 How to Cite?
AbstractBiomolecular nucleophilic substitution reactions, SN2, are fundamental and commonplace in chemistry. It is the well-documented experimental finding in the literature that vicinal substitution with bulkier groups near the reaction center significantly slows the reaction due to steric hindrance, but theoretical understanding in the quantitative manner about factors dictating the SN2 reaction barrier height is still controversial. In this work, employing the new quantification approach that we recently proposed for the steric effect from the density functional theory framework, we investigate the relative contribution of three independent effects-steric, electrostatic, and quantum-to the SN2 barrier heights in gas phase for substituted methyl halide systems, R1R2R3CX, reacting with the fluorine anion, where R1, R2, and R3 denote substituting groups and X = F or Cl. We found that in accordance with the experimental finding, for these systems, the steric effect dominates the transition state barrier, contributing positively to barrier heights, but this contribution is largely compensated by the negative, stabilizing contribution from the quantum effect due to the exchange-correlation interactions. Moreover, we find that it is the component from the electrostatic effect that is linearly correlated with the SN2 barrier height for the systems investigated in the present study. In addition, we compared our approach with the conventional method of energy decomposition in density functional theory as well as examined the steric effect from the wave function theory for these systems via natural bond orbital analysis. © 2010 American Chemical Society.
Persistent Identifierhttp://hdl.handle.net/10722/132169
ISSN
2015 Impact Factor: 2.883
2015 SCImago Journal Rankings: 1.231
PubMed Central ID
ISI Accession Number ID
Funding AgencyGrant Number
UNC EFRC
U.S. Department of Energy, Office of Science, Office of Basic Energy SciencesDE-SC0001011
National Institute of HealthHL-06350
NSFFRG DMR-0804549
NIH, NIEHS
Funding Information:

Helpful discussion with Daniel Ess, Robert G. Parr, and Cynthia K. Schauer of University of North Carolina at Chapel Hill; Robert C. Morrison of East Carolina University; Paul W. Ayer of McMaster University, Canada; and Stephen L. Craig of Duke University is gratefully acknowledged. This work was supported in part by UNC EFRC: Solar Fuels and Next Generation Photovoltaics, an Energy Frontier Research Center funded by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences under Award No. DE-SC0001011; the National Institute of Health (HL-06350); NSF (FRG DMR-0804549); and the Intramural Research Program of NIH, NIEHS. We acknowledge the use of the computational resources provided by the Research Computing Center at University of North Carolina at Chapel Hill. Part of the work was presented in the 50th Sanibel Symposium at St. Thomas Island, GA.

References

 

DC FieldValueLanguage
dc.contributor.authorLiu, Sen_HK
dc.contributor.authorHu, Hen_HK
dc.contributor.authorPedersen, LGen_HK
dc.date.accessioned2011-03-21T08:58:20Z-
dc.date.available2011-03-21T08:58:20Z-
dc.date.issued2010en_HK
dc.identifier.citationJournal Of Physical Chemistry A, 2010, v. 114 n. 18, p. 5913-5918en_HK
dc.identifier.issn1089-5639en_HK
dc.identifier.urihttp://hdl.handle.net/10722/132169-
dc.description.abstractBiomolecular nucleophilic substitution reactions, SN2, are fundamental and commonplace in chemistry. It is the well-documented experimental finding in the literature that vicinal substitution with bulkier groups near the reaction center significantly slows the reaction due to steric hindrance, but theoretical understanding in the quantitative manner about factors dictating the SN2 reaction barrier height is still controversial. In this work, employing the new quantification approach that we recently proposed for the steric effect from the density functional theory framework, we investigate the relative contribution of three independent effects-steric, electrostatic, and quantum-to the SN2 barrier heights in gas phase for substituted methyl halide systems, R1R2R3CX, reacting with the fluorine anion, where R1, R2, and R3 denote substituting groups and X = F or Cl. We found that in accordance with the experimental finding, for these systems, the steric effect dominates the transition state barrier, contributing positively to barrier heights, but this contribution is largely compensated by the negative, stabilizing contribution from the quantum effect due to the exchange-correlation interactions. Moreover, we find that it is the component from the electrostatic effect that is linearly correlated with the SN2 barrier height for the systems investigated in the present study. In addition, we compared our approach with the conventional method of energy decomposition in density functional theory as well as examined the steric effect from the wave function theory for these systems via natural bond orbital analysis. © 2010 American Chemical Society.en_HK
dc.languageengen_US
dc.publisherAmerican Chemical Society. The Journal's web site is located at http://pubs.acs.org/jpcaen_HK
dc.relation.ispartofJournal of Physical Chemistry Aen_HK
dc.subject.meshGases - chemistry-
dc.subject.meshMolecular Structure-
dc.subject.meshQuantum Theory-
dc.subject.meshStatic Electricity-
dc.subject.meshThermodynamics-
dc.titleSteric, quantum, and electrostatic effects on SN2 reaction barriers in gas phaseen_HK
dc.typeArticleen_HK
dc.identifier.openurlhttp://library.hku.hk:4550/resserv?sid=HKU:IR&issn=1089-5639&volume=114&issue=18&spage=5913&epage=5918&date=2010&atitle=Steric,+quantum,+and+electrostatic+effects+on+S(N)2+reaction+barriers+in+gas+phase-
dc.identifier.emailHu, H:haohu@hku.hken_HK
dc.identifier.authorityHu, H=rp00707en_HK
dc.description.naturelink_to_OA_fulltext-
dc.identifier.doi10.1021/jp101329fen_HK
dc.identifier.pmid20377265en_HK
dc.identifier.pmcidPMC2865848-
dc.identifier.scopuseid_2-s2.0-77952157411en_HK
dc.identifier.hkuros176618en_US
dc.relation.referenceshttp://www.scopus.com/mlt/select.url?eid=2-s2.0-77952157411&selection=ref&src=s&origin=recordpageen_HK
dc.identifier.volume114en_HK
dc.identifier.issue18en_HK
dc.identifier.spage5913en_HK
dc.identifier.epage5918en_HK
dc.identifier.eissn1520-5215-
dc.identifier.isiWOS:000277280400035-
dc.publisher.placeUnited Statesen_HK
dc.identifier.scopusauthoridLiu, S=7409463290en_HK
dc.identifier.scopusauthoridHu, H=7404097564en_HK
dc.identifier.scopusauthoridPedersen, LG=7201717880en_HK

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