Photolysis of Carbonyl Diisocyanate: Generation of Isocyanatocarbonyl Nitrene and Diazomethanone |
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| Authors: | Dr Qifan Liu Hongmin Li Zhuang Wu Dingqing Li Dr Helmut Beckers Dr Guntram Rauhut Prof Dr Xiaoqing Zeng |
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| Institution: | 1. College of Chemistry, Chemical Engineering and Materials Science, Soochow University, Suzhou, P.?R. China;2. Institut für Chemie und Biochemie, Freie Universit?t Berlin, Berlin, Germany;3. Institute of Theoretical Chemistry, University of Stuttgart, Stuttgart, Germany |
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| Abstract: | The stepwise decomposition of carbonyl diisocyanate, OC(NCO)2, has been studied by using IR spectroscopy in solid argon matrices at 16 K. Upon irradiation with an ArF laser (λ=193 nm), carbonyl diisocyanate split off CO and furnished a new carbonyl nitrene, OCNC(O)N, in its triplet ground state. Two conformers of the nitrene, syn and anti, that were derived from the two conformers of OC(NCO)2 (62 % syn–syn and 38 % syn–anti) were identified and characterized by combining IR spectroscopy and quantum chemical calculations. Subsequent irradiation with visible light (λ>395 nm) caused the Curtius rearrangement of the nitrene into OCNNCO. In addition to the expected decomposition products, N2 and CO, further photolysis of OCNNCO with the ArF laser yielded NOCN, through a diazomethanone (NNCO) intermediate. To further validate our proposed reaction mechanism, ArF‐laser photolysis of the closely related NNNNCO and cyclo‐N2CO in solid argon matrices were also studied. The observations of NOCN and in situ CO‐trapped product OCNNCO provided indirect evidence to support the initial generation of NNCO as a common intermediate during the laser photolysis of OCNNCO, NNNNCO, and cyclo‐N2CO. |
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| Keywords: | IR spectroscopy matrices nitrenes photochemistry reactive intermediates |
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