Chemistry of low valent silicon

The preparation of NHC·SiCl2 and its reaction with various reagents is reported (NHC = N-heterocyclic carbene). A comparable reaction is used for preparing LSiCl from LSiHCl2 and NHC (L = PhC(NtBu)2). The reduction of LSiCl results in the formation of the inter-connected bis-silylene of composition LSi:–Si:L. The latter compound reacts with P4 and AdCP to LSiP2SiL and LSi(Ad)CPSiL, respectively. Treatment of NHC·SiCl2 with 2,6-Ar2C6H3N3 (Ar = 2,6-iPr2C6H3 or 2,4,6-iPr3C6H2) resulted in the NHC·(SiCl2)N2,6-Ar2C6H3. The reduction of the latter yields the bis-silylene. This cyclic bis-silylene of composition (2,6-Ar2C6H3NSi:)2 contains a four-membered N2Si2 ring with two coordinate silicon. Treatment of LSiN(SiMe3)2 with P4 results in the acyclic 6π system L((Me3Si)2N)SiP–PP–PSi(N(SiMe3)2)L under opening of the P4 tetraeder. Metal complexes of silylenes with Co, V, and Ni are reported.

The preparation of NHC SiCl2 by dehydrochlorination and its reaction with various reagents is reported (NHC = N-heterocyclic carbene). A comparable reaction is used for preparing LSiCl from LSiHCl2 (L = PhC(NtBu)2) and NHC. The reduction of LSiCl results in the formation of the inter-connected bis-silylene of composition LSi:–Si:L.Figure optionsDownload as PowerPoint slideHighlights
► N-heterocyclic carbene stabilized SiCl2.
► Dehydrochlorination for the preparation of silylenes.
► Syntheses of cyclic and acyclic bissilylenes.
►  Conversion of the P4 molecule to an acyclic P4 chain.
► Transition metal complexes with silylenes as ligands.