Catalogo Articoli (Spogli Riviste)

OPAC HELP

Titolo:
AB-INITIO STUDIES OF THE RING-OPENING REACTION OF THE CYCLOBUTENE RADICAL-CATION
Autore:
WIEST O;
Indirizzi:
UNIV NOTRE DAME,DEPT CHEM & BIOCHEM NOTRE DAME IN 46556
Titolo Testata:
Journal of the American Chemical Society
fascicolo: 24, volume: 119, anno: 1997,
pagine: 5713 - 5719
SICI:
0002-7863(1997)119:24<5713:ASOTRR>2.0.ZU;2-A
Fonte:
ISI
Lingua:
ENG
Soggetto:
QUADRATIC CONFIGURATION-INTERACTION; CORRELATED MOLECULAR CALCULATIONS; GAUSSIAN-BASIS SETS; ELECTROCYCLIC REACTIONS; PERICYCLIC-REACTIONS; PERTURBATION-THEORY; CYCLO-ADDITIONS; DIELS-ALDER; CASSCF; REARRANGEMENT;
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Science Citation Index Expanded
Citazioni:
73
Recensione:
Indirizzi per estratti:
Citazione:
O. Wiest, "AB-INITIO STUDIES OF THE RING-OPENING REACTION OF THE CYCLOBUTENE RADICAL-CATION", Journal of the American Chemical Society, 119(24), 1997, pp. 5713-5719

Abstract

The ring-opening reaction of the cyclobutene radical cation was studied by using Hartree-Fock and density functional theory as well as various correlated MO methods. The species involved in three different mechanism-a concerted C-2-symmetric, a concerted C-1-symmetric, and a stepwise C-1-symmetric pathway- have been considered. It is shown that any symmetric pathway is dominated by state symmetry election rules which determine the outcome of the reaction. The concerted C-2-symmetric pathway is subject to a pseudo Jahn-Teller distortion and leads to trans-butadiene. This pathway is approximately 5 kcal/mol higher in energythan the concerted C-1-symmetric pathway, leading to cis-butadiene. Based on the results presented here, the stepwise C-1-symmetric or ''nonelectrocyclic'' pathway discussed in the literature is an artifact ofan overestimation of the radical stability by MP2 and minimum basis set ab initio methods. It is therefore concluded that the ring opening of the cyclobutene radical cation proceeds via a concerted, unsymmetric pathway to cis-butadiene. The results from Becke3LYP calculations for geometries, energies, and isotropic hyperfine coupling constants arein good agreement with the available experimental data and with QCISD(T)/QCISD calculations. The results from the different methods are discussed with respect to the experimental data, and the implications of the data presented here for future computational studies of radical ion reactions are considered.

ASDD Area Sistemi Dipartimentali e Documentali, Università di Bologna, Catalogo delle riviste ed altri periodici
Documento generato il 04/12/20 alle ore 16:10:22