Photolysis of Carbonyl Diisocyanate: Generation of Isocyanatocarbonyl Nitrene and Diazomethanone

作者:Liu Qifan; Li Hongmin; Wu Zhuang; Li Dingqing; Beckers Helmut; Rauhut Guntram; Zeng Xiaoqing
来源:Chemistry-An Asian Journal, 2016, 11(20): 2953-2959.
DOI:10.1002/asia.201601073

摘要

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 (lambda = 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 (lambda > 395 nm) caused the Curtius rearrangement of the nitrene into OCNNCO. In addition to the expected decomposition products, N-2 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.