title: Early events in the photochemistry of 1,2,3-thiadiazole studied by ultrafast time-resolved UV-vis and IR spectroscopies.
abstract: Photochemistry of 4-methyl-5-carboethoxy-1,2,3-thiadiazole (MCT) in solution was studied at room temperature using UV-vis and IR transient absorption spectroscopies (λ(ex) = 266 nm). Three deactivation pathways are discussed: thiirene formation, thioketene generation, and the internal conversion by repopulating MCT in the ground state. Ultrafast techniques show a very fast rise (<0.4 ps) of thiirene species in acetonitrile, possibly as a result of a rearrangement in the singlet excited state of MCT in concert with molecular nitrogen extrusion. The remarkable stability of thiirene in solution on a millisecond time scale is limited by the process of dimerization (thiirene-thiirene, thiirene-thioketene). NMR analysis permitted identification of stable photoproducts as 1,3-dithietane, 1,3-dithiole, and thiophene derivatives.
authors: Quantum Electronics Laboratory, Faculty of Physics, Adam Mickiewicz University, Poznan, Poland. gotardb@amu.edu.pl
authors: Gotard
authors: G
authors: Burdzinski
authors: Michel
authors: M
authors: Sliwa
authors: Yunlong
authors: Y
authors: Zhang
authors: Stéphanie
authors: S
authors: Delbaere
mesh_terms: D000097:Acetonitriles / Q000737:chemistry; D019281:Dimerization; D009682:Magnetic Resonance Spectroscopy; D015394:Molecular Structure; D009584:Nitrogen / Q000737:chemistry; D055668:Photochemical Processes; D011789:Quantum Theory; D013055:Spectrophotometry, Infrared; D013056:Spectrophotometry, Ultraviolet; D013830:Thiadiazoles / Q000737:chemistry*; D013876:Thiophenes / Q000737:chemistry*; D013997:Time Factors
chemical_list: D000097:Acetonitriles; D013830:Thiadiazoles; D013876:Thiophenes; D009584:Nitrogen; C032159:acetonitrile