Liu Qifan, Li Hongmin, Wu Zhuang, Li Dingqing, Beckers Helmut, Rauhut Guntram, Zeng Xiaoqing
College of Chemistry, Chemical Engineering and Materials Science, Soochow University, Suzhou, 215123, P. R. China.
Institut für Chemie und Biochemie, Freie Universität Berlin, Berlin, 14195, Germany.
Chem Asian J. 2016 Oct 20;11(20):2953-2959. doi: 10.1002/asia.201601073. Epub 2016 Sep 21.
The stepwise decomposition of carbonyl diisocyanate, OC(NCO) , 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) (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, N 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-N CO 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-N CO.
利用红外光谱在16K的固体氩基质中研究了羰基二异氰酸酯OC(NCO)₂的逐步分解。用ArF激光（λ=193nm）照射时，羰基二异氰酸酯分解出CO，并生成一种处于三重态基态的新的羰基氮烯OCNC(O)N。通过结合红外光谱和量子化学计算，鉴定并表征了氮烯的两种构象异构体顺式和反式，它们分别源自OC(NCO)₂的两种构象异构体（62%顺-顺式和38%顺-反式）。随后用可见光（λ>395nm）照射导致氮烯发生柯提斯重排生成OCNNCO。除了预期的分解产物N₂和CO外，用ArF激光对OCNNCO进行进一步光解，通过重氮甲酮（NNCO）中间体生成了NOCN。为了进一步验证我们提出的反应机理，还研究了在固体氩基质中对密切相关的NNNNCO和环-N₂CO进行ArF激光光解。对NOCN和原位CO捕获产物OCNNCO的观察提供了间接证据，支持在OCNNCO、NNNNCO和环-N₂CO的激光光解过程中最初生成NNCO作为共同中间体。
