N-nacnac stabilized tetrylenes: access to silicon hydride systems via migration processes

The use of an amino-functionalized β-diketiminate (′N-nacnac′) ligand in low-valent silicon chemistry is investigated. In particular, the use of (L^Dipp)SiCl (L^Dipp=HC{(Me₂N)CNDipp}₂) to generate silicon-containing products via metathesis chemistry is explored, in light of previously reported complications arising from heterocycle ring contraction. In the case of Na[C₅H₅], chloride metathesis is accompanied not by rearrangement of the N-nacnac ligand, but by a C-to-Si hydrogen migration process, generating the hydridosilicon(IV) species (L^Dipp)Si(H)(C₅H₄), which features a silafulvene core. The potential intermediate arising from initial chloride/cyclopentadienide substitution can be modelled by the chemistry of the corresponding Ge(II) and Sn(II) systems, which generate (L^Dipp)E(η¹−C₅H₅) (E=Ge, Sn) via straightforward metathesis chemistry. A Si(II) hydride species can be generated from (L^Dipp)SiCl via metathesis by making use of a d-block reagent which can act as both hydride source and coordinative trap for (L^Dipp)SiH. Thus, the reaction of (L^Dipp)SiCl with K[(η⁵−C₅H₄Me)Mn(CO)₂H] leads to the formation of (η⁵−C₅H₄Me)Mn(CO)₂{Si(H)L^Dipp} – the first silylene complex containing this half-sandwich manganese fragment.