Silylene reaction with molecular oxygen

While many examples of carbene oxidations have been reported, only four papers on the reaction of silylenes 1 with molecular oxygen have been published. The limited number of experimental studies on the oxygenation of silylenes is mainly due to the lack of suitable precursors.The photolysis of matrix-isolated trisilanes produces silylenes in close proximity to disilenes or other products of the precursor decomposition rather than matrix-isolated silylenes.Gas-phase thermolysis of disilanes and other thermal precursors requires very high temperatures, while the photolysis of diazidosilanes requires short-wavelength UV irradiation. In all of these cases, the yields of silylenes are rather poor. 

Silylenes 1 and silenes 2 are generally highly reactive species that can only be isolated under normal laboratory conditions if protected by bulky substituentsJ But even then these molecules rapidly react with molecular oxygen at room temperature and thus have to be stored under an inert gas atmosphere. The oxidation often leads to complex product mixtures or to complete combustion. At low temperatures, on the other hand, the reaction becomes slow and is difficult to follow. Thus, only a few studies on the mechanisms of the oxidation of stable silenes and silylenes have been published. 

As primary products of the reaction of silylenes with molecular oxygen the formation of either silanone (9-oxides 3 or the dioxasiliranes 4 can be expected. The homologous carbenes react exclusively to give carbonyl (9-oxides 5 which rearrange photochemically to dioxiranes 6 (Scheme 5.1). ... 

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