Cyclopolysilanes photolysis

Oxidation of 44 is completely inhibited by the addition of a small amount of 2,4,6-tri-f-butylphenol. Consequently, the oxidation of the Si—Si bond with oxygen displays the following features 1) a Si—Si bond which is either angle-strained or substituted with more than two fluorine atoms is easily oxidized 2) a radical mechanism is operative 3) the insertion of oxygen into the Si—Si bond proceeds stereospecifically . Incorporation of molecular oxygen was also observed in the direct photolysis of the cyclopolysilanes 80 and 81 (equations 88 and 89) . ... 

There have been a number of routes to silylenes that are related to the simple photolysis of the precursors. The principal photoprocesses of alkylpolysilanes in solution are (a) chain abridgement through ehmination of silylene and (b) chain scission by Si—Si bond homolysis. The photolysis of trisilanes [RR Si(SiMe3)2] or cyclopolysilanes [(RR Si) ] is a well-established method for the generation of silylene (Scheme 14.7). ... 

As mentioned above, the photolysis of cyclopolysilanes was the earliest method for the generation of silylenes in matrices. Indeed, such extrusions from oligosilanes were used... 

A third photochemical access to silylenes, beside the isomerization of silenes and the photolysis of tri- or cyclopolysilanes, is the irradiation of geminal diazidosilanes, which under nitrogen loss often gives the corresponding divalent silicon species. However, silan-imines are frequent by-products164 or in some cases even the only products (Section IV). 

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