title: Photolysis of Matrix-Isolated 4-R-1,2,4-triazoline-3,5-diones: Identification of Aziridine-2,3-dione Transients.
abstract: Matrix-isolated 4-methyl-1,2,4-triazolinedione 1a and 4-phenyl-1,2,4-triazolinedione 1b were photolyzed at lambda >/= 335 nm and lambda >/= 310 nm, respectively. The reactions induced by photolysis were monitored by FT-IR spectroscopy. The isocyanates 2a and 2b are always the more abundant products with carbon monoxide. Methyl- and phenylaziridine-2,3-diones (3a and 3b) were detected as minor, but well-identified reaction products. The IR experimental absorption bands were assigned by comparison with literature data and with simulated infrared spectra obtained by ab initio calculation at the 6-31G level. Stable at the matrix temperature (10 K), 3a and 3b photolyzed to isocyanates and CO when irradiated at lambda >/= 230 nm. Irradiation of 2b at this wavelength induces its decomposition. The kinetic data show that the rate constant process 1a --> 2a is faster than the 1a --> 3a process (3.29 x 10(-)(3 )and 2.35 x 10(-)(4)min(-)(1) respectively).
authors.affiliation: Laboratoire de Spectrométries et Dynamique Moléculaire, URA 773, Physique des Interactions Ioniques et Moléculaires, Université de Provence, Case 542, 13397 Marseille Cedex 20, France.
authors.forename: Florence
authors.initials: F
authors.lastname: Risi
authors.forename: Louis
authors.initials: L
authors.lastname: Pizzala
authors.forename: Micheline
authors.initials: M
authors.lastname: Carles
authors.forename: Patrick
authors.initials: P
authors.lastname: Verlaque
authors.forename: Jean-Pierre
authors.initials: JP
authors.lastname: Aycard