Photoreactions of Alkyls and Aryls

In certain cases the alkyl and aryl complexes themselves undergo photoreactions. One of the earliest such discoveries is the report that methane is obtained by photolysis of ( / -cp)2MMe2 (M = Ti, Zr, Hf) (Refs. 59 and 60)  

Photolysis of ( / -cp)2 nMe2 in the presence of diphenylacetylene gives both the insertion and the metallocyclic products  

When the perfluorinated diphenylacetylene is used, the insertion product is selectively formed. A metallocycle can also be obtained by photolysis of ( / -cp)2TiMe2 in the presence of elemental sulfur  

Although the photolysis of OsMe2(CO)4, like ()/ -cp)2TiMe2, does not lead to the formation of ethane/ photolysis of the benzyl co-balt(III) complex Co(CH2Ph)(CN)5 at 313 nm does result in the formation of bibenzyl  

If the irradiation is carried out in the presence of oxygen, the organic product is benzaldehyde. These observations can be explained on the basis of an initial photohomolysis of the cobalt-carbon bond to give a benzyl radical, which then either dimerizes or is trapped by oxygen. A similar homolysis of an Rh-C bond explains the photoaquation of RhEt(H20)(NH3)3 to Rh(H20)2(NH3)i (Ref. 68)  

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