Early Events in the Photochemistry of 1,2,3-Thiadiazole Studied by Ultrafast Time-Resolved UV鈥揤is and IR Spectroscopies

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• 作者：Gotard Burdzinski ; Michel Sliwa ; Yunlong Zhang ; St茅phanie Delbaere
• 刊名：Journal of Physical Chemistry A
• 出版年：2011
• 出版时间：December 22, 2011
• 年：2011
• 卷：115
• 期：50
• 页码：14300-14305
• 全文大小：849K
• 年卷期：v.115,no.50(December 22, 2011)
• ISSN：1520-5215

文摘

Photochemistry of 4-methyl-5-carboethoxy-1,2,3-thiadiazole (MCT) in solution was studied at room temperature using UV鈥搗is and IR transient absorption spectroscopies (位_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鈥搕hiirene, thiirene鈥搕hioketene). NMR analysis permitted identification of stable photoproducts as 1,3-dithietane, 1,3-dithiole, and thiophene derivatives.