title: Application of radical cation spin density maps toward the prediction of photochemical reactivity between N-methyl-1,2,4-triazoline-3,5-dione and substituted benzenes.
abstract: Visible light irradiation of N-methyl-1,2,4-triazoline-3,5-dione in the presence of substituted benzenes is capable of inducing substitution reactions where no reaction takes place thermally. In addition to the formation of 1-arylurazole products resulting from ring substitution, side-chain substitution occurs in some cases where benzylic hydrogens are accessible to form benzylic urazole products. Formation of both types of products is most consistent with the involvement of a common intermediate, a radical ion pair, generated from photoexcitation of an initially formed charge-transfer complex. The charge-transfer complexes have been observed spectroscopically. Additionally, application of a modified Rehm-Weller model suggests that the electron-transfer processes are feasible for all of the substrates examined. In most cases, the spin density maps of the aromatic radical cation intermediates calculated at the DFT UB3LYP/6-31G* level are excellent predictors of the observed product distributions.
authors.affiliation: Department of Chemistry, Berry College, 2277 Martha Berry Highway, Mount Berry, Georgia 30149, USA. gbreton@berry.edu
authors.forename: Gary W
authors.initials: GW
authors.lastname: Breton
authors.forename: Kevin R
authors.initials: KR
authors.lastname: Hoke
mesh_terms: D001555:Benzene Derivatives / Q000737:chemistry*; D002412:Cations / Q000737:chemistry; D005609:Free Radicals / Q000737:chemistry; D008027:Light; D015394:Molecular Structure; D055668:Photochemical Processes; D011789:Quantum Theory; D014230:Triazoles / Q000138:chemical synthesis / Q000737:chemistry*
chemical_list: D001555:Benzene Derivatives; D002412:Cations; D005609:Free Radicals; D014230:Triazoles; C421465:urazole