par Delaby, Alain ;Rondelez, Daniel ;Boué, Stéphane
Référence Journal of photochemistry, 4, 5-6, page (399-406)
Publication Publié, 1975-11
Article révisé par les pairs
Résumé : Theory and e.p.r. experiments show that upon electronic excitation, benzene loses its D6h symmetry; the description of the 1B2u state by a 1,3-diradical (with zwitterionic character) and that of the 3B1u state by a 1,4- or a 1,2-diradical has been proposed and found viable. However, it would be interesting to know whether these diradicals can be considered as such with respect to the chemical reactivity of the states. The chemical quenching of excited benzene by Me3SnH, a species highly reactive towards free radicals, has thus been attempted. We obtained no evidence for any reaction of the triplet benzene whilst the singlet did react but only scarcely; instead the tin hydride acted as a moderate intersystem crossing catalyst as evidenced by the fluorescence quenching and by the enhanced ΦP/ΦF ratio observed for benzene. The decay to the ground state in fluid solutions ultimately involves a step of energy transfer to the hydride which partly decomposes. Similar results were obtained for the intramolecular quenching studied on β-phenethyldimethyltin hydride. © 1975.