NHC-coordinated silagermenylidene functionalized in allylic position and its behaviour as a ligand

Abstract

Vinylidenes are common in transition metal chemistry with catalytic applications in alkene and alkyne metathesis. We report here the isolation of a heavier analogue of vinylidene, an α-chlorosilyl functionalized silagermenylidene stabilized by an N-heterocyclic carbene (NHC). Silagermenylidene (Tip₂Cl)Si-(Tip)SiGe·NHC^iPr₂Me₂ (4-E/Z; Tip = 2,4,6-ⁱPr₃C₆H₂; NHC^iPr₂Me₂ = 1,3-diisopropyl-4,5-dimethylimidazol-2-ylidene) is available as an E/Z-equilibrium mixture from Tip₂SiSi(Tip)Li and NHC^iPr₂Me₂·GeCl₂. Reaction of 4-E/Z with Fe₂(CO)₉ affords a silagermenylidene Fe(CO)₄ complex, which slowly isomerizes to its E-isomer at 25 °C. A rearranged Fe(CO)₃ complex with an allylic SiGeSi ligand is obtained as a side product at 65 °C.