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 AdCtriple bond; length of mdashP 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)double bond; length as m-dashN2,6-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)Sidouble bond; length as m-dashP–Pdouble bond; length as m-dashP–Pdouble bond; length as m-dashSi(N(SiMe3)2)L under opening of the P4 tetraeder. Metal complexes of silylenes with Co, V, and Ni are reported.