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Titolo:
Quantum mechanical study of the ring-closing reaction of the hexatriene radical cation
Autore:
Radosevich, AT; Wiest, O;
Indirizzi:
Univ Notre Dame, Dept Chem & Biochem, Notre Dame, IN 46556 USA Univ Notre Dame Notre Dame IN USA 46556 Biochem, Notre Dame, IN 46556 USA
Titolo Testata:
JOURNAL OF ORGANIC CHEMISTRY
fascicolo: 17, volume: 66, anno: 2001,
pagine: 5808 - 5813
SICI:
0022-3263(20010824)66:17<5808:QMSOTR>2.0.ZU;2-8
Fonte:
ISI
Lingua:
ENG
Soggetto:
POTENTIAL-ENERGY SURFACE; DIELS-ALDER REACTION; ELECTRON-TRANSFER; OPENING REACTION; AB-INITIO; REARRANGEMENTS; CYCLOBUTANE; SYSTEMS;
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Life Sciences
Physical, Chemical & Earth Sciences
Citazioni:
42
Recensione:
Indirizzi per estratti:
Indirizzo: Wiest, O Univ Notre Dame, Dept Chem & Biochem, Notre Dame, IN 46556 USA Univ Notre Dame Notre Dame IN USA 46556 Notre Dame, IN 46556 USA
Citazione:
A.T. Radosevich e O. Wiest, "Quantum mechanical study of the ring-closing reaction of the hexatriene radical cation", J ORG CHEM, 66(17), 2001, pp. 5808-5813

Abstract

The ring-closing reaction of hexatriene radical cation 1(.+) to 1,3-cyclohexadiene radical cation 2(.1) was studied computationally at the B3LYP/6-31G* and QCISD(T)/6-311G*//QCISD/6-31G* levels of theory. Both, concerted andstepwise mechanisms were initially considered for this reaction. Upon evaluation at the B3LYP level of theory, three of the possible pathways-a concerted C-2-symmetric via transition structure 3(.+) and stepwise Ci-symmetricpathways involving three-membered ring intermediate 5(.+) and four-membered ring intermediate 6(.+)-were rejected due to high-energy stationary points along the reaction pathway. The two remaining pathways were found to be of competing energy. The first proceeds through the asymmetric, concerted transition structure 4(.+) with an activation barrier E-a = 16.2 kcal/mol andan overall exothermicity of -23.8 kcal/mol. The second pathway, beginning from the cis,cis,trans rotamer of 1(.+), proceeds by a stepwise pathway to the cyclohexadiene product with an overall exothermicity of - 18.6 kcal/mol. The activation energy for the rate-determining step in this process, the formation of the intermediate bicyclo[3.1.0]hex-2-ene via transition structure 9(.+), was found to be 20.4 kcal/mol. More rigorous calculations of a smaller subsection of the potential energy hypersurface at the QCISD(T)//QCISD level confirmed these findings and emphasized the importance of conformational control of the reactant.

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Documento generato il 04/12/20 alle ore 16:22:21