Insertion Behavior of Dialkylgermylene Ge(FluTMS)2 in Different E–X σ Bonds (E = Au, Si, Ge, Sn) and Its Relevance for Germanium Cluster Formation

Abstract

We present the insertion behavior of the alkyl-substituted germylene Ge(Flu^TMS)₂ in different E–X σ bonds (E = Au, Si, Ge, Sn), first with the isolation of the germylgold complex (Flu^TMS)₂Ge(Cl)AuPPh₃. Afterward, the oxidative addition of GeCl₄ to Ge(Flu^TMS)₂ gives the digermane (Flu^TMS)₂Ge(Cl)GeCl₃, followed by a reductive elimination of GeCl₂ and the formation of the oxidation product (Flu^TMS)₂GeCl₂. A comparable behavior is observed, with the homologues ECl₄ (E = Si, Sn) stopping at different steps of the reaction. The formation of the germylgermylene (Flu^TMS)₂Ge(Cl)GeCl starting from Ge(Flu^TMS)₂ and GeCl₂·dioxane is also spectroscopically observable, followed by ligand rearrangements to the tetramer [Flu^TMSGeCl]₄. Adding a phosphine as the Lewis base has a direct influence on the stability and structure of (Flu^TMS)₂Ge(Cl)GeCl, leading to the formation of Flu^TMSGeCl·PEt₃ as a stable product. Subsequent investigations of Ge(Flu^TMS)₂ with a metastable Ge(I)Br solution show that at a ratio of 6:1 GeBr/Ge(Flu^TMS)₂ the alkyl-substituted germylene no longer acts as a redox-active agent but as a cluster building block. This link and the involvement of a germylene in insertion reactions give an indication of how the construction or expansion of Ge cluster species can operate.