uu.seUppsala University Publications
Change search
ReferencesLink to record
Permanent link

Direct link
Role of Electronic Curve Crossing of Benzene S-1 State in the Photodissociation of Aryl Halides, Effect of Fluorination: RASSI-SO MS-CASPT2 Study
Department of Theoretical Chemistry, Lund University.ORCID iD: 0000-0001-7567-8295
2009 (English)In: International Journal of Quantum Chemistry, ISSN 0020-7608, E-ISSN 1097-461X, Vol. 109, no 9, 1962-1974 p.Article in journal (Refereed) Published
Abstract [en]

An ab initio study of the role of electronic curve crossing of benzene S-1 state in the photo dissociation dynamics of the iodobenzene and effect of fluorination is presented. Two dissociative life times observed in iodobenzene is attributed to the coupled repulsive potential energy curves of the low-lying n-sigma*, pi-sigma*, pi-pi* states. The direct channel is attributed to the alkyl like transition and the indirect channel is attributed to the mixing of the alkyl like transitions with the low lying benzene pi-pi* transitions. Fluorination of iodobenzene results in a substantial increase in the direct channel product. To analyze the possible role of electronic curve crossing of these transitions, potential energy curves of low-lying n-sigma*, pi-sigma*, pi-pi* states were studied including spin-orbit and relativistic effects using the Restricted Active Space state interaction multistate complete active space perturbation theory (RASSI-MS-CASPT2) method. Crossing behavior of spin-free and spin-orbit potential energy curves was analyzed for the role of the benzene S-1 state. Our results indicate the curve crossing region to be around 2.00-2.35 angstrom for both C6H5I and C6F5I. Analysis of effect of fluorination on the energies of states corresponding to benzene pi-pi* and n-sigma* transitions suggests an increase in the energy of benzene pi-pi* states and a decrease in the energy of the states corresponding to n-sigma* transitions. Increased spin-orbit gap, increased separation of the benzene S-1(pi-pi*) state and n-sigma* states in the region of curve crossing, lesser mixing of the pi-pi* and n-sigma* states, an order of magnitude decrease in the transition strength to the benzene singlet transition all contributed to the observed Substantial increase in the quantum yield of the direct channel product on fluorination of aryl halides.

Place, publisher, year, edition, pages
2009. Vol. 109, no 9, 1962-1974 p.
Keyword [en]
photodissociation dynamics, Iodobenzene, C6F5I, electric curve crossing, ab initio, multireference, relativistic, spin-orbit, MS-CASPT2, RASSI-SO, DHH
National Category
Chemical Sciences
URN: urn:nbn:se:uu:diva-143870DOI: 10.1002/qua.22033OAI: oai:DiVA.org:uu-143870DiVA: diva2:394354
Available from: 2011-02-02 Created: 2011-01-25 Last updated: 2015-01-08Bibliographically approved

Open Access in DiVA

No full text

Other links

Publisher's full text

Search in DiVA

By author/editor
Lindh, Roland
In the same journal
International Journal of Quantum Chemistry
Chemical Sciences

Search outside of DiVA

GoogleGoogle Scholar
The number of downloads is the sum of all downloads of full texts. It may include eg previous versions that are now no longer available

Altmetric score

Total: 416 hits
ReferencesLink to record
Permanent link

Direct link