Model calculations of matrix effects on the conversion of propene radical cations into allyl radicals in halocarbon matrices
Uppsala University1997 (English)In: Acta Chemica Scandinavica, ISSN 0904-213X, Vol. 51, no 2, 242-248 p.Article in journal (Refereed) Published
A comparative study has been undertaken of the conversion of propene radical cations into allyl radicals in the gas phase and in CCl4 and CF4 matrices, The semiempirical UHF/PM3 method, complemented with ab initio PMP2/3-21G and PMP2/6-31G(d, p) calculations, is employed to model this process, which is observed to occur through an ion-molecule reaction by a proton transfer from the propene radical cation to a neutral propene molecule. Single molecules of CCl4 and CF4 are used to model the influence of the corresponding matrices, following two different pathways depending on which proton is transferred. It is found that the reaction in the gas phase occurs without activation energy. In contrast, a barrier is found on the potential energy curve of the reaction in the CCl4 matrix. The strongest interactions are found for CCl4, resulting in a 6.9 kcal mol(-1) activation energy (2.6 kcal mol(-1) for the second pathway). The reaction in CF4 has an intermediate profile with an activation energy of only 2.0 kcal mol(-1) (no barrier for the second pathway). The interactions between the migrating proton and the matrix molecule are interpreted in terms of the basicity of the matrix.
Place, publisher, year, edition, pages
1997. Vol. 51, no 2, 242-248 p.
ELECTRON-SPIN-RESONANCE, SELECTIVE FORMATION, 1-BUTENE, ENERGIES
IdentifiersURN: urn:nbn:se:uu:diva-150599ISI: A1997WJ25300019OAI: oai:DiVA.org:uu-150599DiVA: diva2:407910
Conference Information: 14th International Conference on Radical Ions UPPSALA, SWEDEN, JUL 01-05, 1996 2011-04-012011-04-012011-04-09Bibliographically approved