Masked silylenes

Reactions of a Silylene-Isonitrile Complex as a Masked Silylene. 689... 

As mentioned above, there have been no examples of stable diarylsilylene although dialkyl- or diamino-substituted silylenes are now available as stable crystalline compounds. However, Tokitoh et al. found that the overcrowded diarylsilylene-isonitrile complexes 139 act as a free silylene 138 in solution even at room temperature. Since there is a severe limitation in a study concerning the reactivities of silylenes under the conventional generating conditions, the reactivity of silylene-isonitrile complexes 139 as a masked silylene is of great interest. 

Consequently, the reactivity of silylene-isonitrile complexes 139 as a masked silylene may provide us with not only a new and useful synthetic building block for a variety of organosUicon compounds but also a new research field in silylene chemistry. 

Polysilanes (or polysilylenes) are usually prepared by the Wurtz-type couphng reaction of dichlorodialkylsilanes or, alternatively, via a transition metal-catalyzed dehydrogenation of dialkylsilanes both approaches often exhibit difficulties in terms of controlling the molecular weight and chain-structure, however. Nonetheless, by using masked silylene monomers (l-phenyl-7,8-disilabicyclo[2.2.2]octa-2,5-dienes), a series of novel, well-defined linear poly(silylene)s (M /Mn 1.3) was successfully obtained via an anionic ROP (Scheme 5.11) [147-150]. 

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