Polyhalomethanes, photolysis

Transient, Spectra Observed in the Flash Photolysis of Polyhalomethanes... 

Unfortunately, it is not possible to determine the maximum vibrational energy content of the methyl radicals produced in the photolysis of methyl iodide. On the basis of the arguments outlined above, strong excitation of the C-H stretching vibration would probably not be anticipated. The methyl radical is planar, however,36 so that its deformation vibration would be excited. On the other hand, the halomethyl radicals are believed to be pyrimidal,37 and unless the grouping has a planar configuration in the excited parent polyhalomethane, deformation would not make any appreciable contribution to the vibrational excitation of the radical. 

Interstitial carbides are prepared in general by photolysis of a metal carbonyl or by reaction of metal carbonyl and a polyhalomethane or other source of the carbide ... 

B.vii. Halocarbenes. Polyhalomethanes can be converted to halocarbenes via photolysis, thermolysis, or treatment with base. When cyclohexene was treated with a mixture of chloromethane and phenylsodium, methylene ( CH2) was formed, and it added to the alkene gave norcarane (336), but in only 3.2% yield.268 Obviously, chloromethane is not the best source of carbenes. Polyhalomethanes give much better results, and the most common method for generating halocarbenes is treatment of dihalomethanes and trihalomethanes with sodium metal or with another base.269... 

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