Spectroscopic studies of various carbene–radical-cations fromed by radiolysis of solutions on halogenocarbons

Cationic species produced in the γ-radiolysis of the halogenocarbon–aryldiazomethane mixtures have been studied at 77 K by electron spin resonance (e.s.r.) and optical absorption spectroscopy. A diphenyldiazomethane radical-cation ([(C6H5)2CN2]+˙) produced by the radiolysis of n-C4H9Cl–(C6H5)2CN2(0.1 mol %) mixtures is found to have an absorption band at 650 nm. When the cation is irradiated with visible light, a different cation is produced which has an absorption spectrum at 390 nm, interpretable in terms of a diphenyl carbene radical-cation ([(C6H5)2C]+˙). A phenyldiazomethane radical cation ([C6H5CHN2]+˙) and a phenylcarbene radical-cation ([C6H5CH]+˙) have absorption bands at 515 and 475 nm, respectively. The e.s.r. spectrum of [(C6H5)2CN2]+˙ cations, produced by the radiolysis of CCl3F–(C6H5)2CN2(0.2 mol %) mixtures at 77 K, shows a broad singlet spectrum. Upon irradiation with visible light the broad spectrum changes into a sharp singlet, which is ascribed to [(C6H5)2C]+˙ cations. Formation of [C6H5CHN2]+˙ and [C6H5CH]+˙ cations has also been studied by e.s.r. spectroscopy. The effect of deuteriation on the e.s.r. spectra has been stuided by use of deuteriated aryldiazomethanes, such as (C6D5)2CN2′ C6H5CDN2′ and C6D5CDN2.