2H-imidazol-2-ylidene : New insights from a matrix-spectroscopic study

Irradiation of 2-diazo-2H-imidazole (1) in a matrix at 10 K with a waveleng th of lambda=313 nm leads to the rapid loss of nitrogen and the formation o f 2H-imidazol-2-ylidene (2). Upon photoexcitation of 2H-imidazol-2-ylidene (2) with wavelengths longer than 570 nm, 1-cyano-1H-azirene (5) can be dete cted, which can be effectively converted into N-cyanoketenimine (4) by irra diation with a wavelength of lambda,= 254 nm. Irradiation of 2-diazo-2H-imi dazole (1) in a xenon matrix generates the complex 2 Xe between 2H-imidazol -2-ylidene and the matrix material. In GO-doped argon matrices the trapping product 2H-imidazol-2-ylideneketene (7) can be observed. On the other hand , flash vacuum pyrolysis of 1 yields only imidazole. 2H-Imidazol-2-ylidene (2) cannot be trapped under thermal conditions.