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(FluTMS)2 in different E-X σ bonds (E = Au, Si, Ge, Sn), first with the isolation of the germylgold complex (FluTMS)2Ge(Cl)AuPPh3. Afterward, the oxidative addition of GeCl4 to Ge(FluTMS)2 gives the digermane (FluTMS)2Ge(Cl)GeCl3, followed by a reductive elimination of GeCl2 and the formation of the oxidation product (FluTMS)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 (FluTMS)2Ge(Cl)GeCl starting from Ge(FluTMS)2 and GeCl2·dioxane is also spectroscopically observable, followed by ligand rearrangements to the tetramer [FluTMSGeCl]4. Adding a phosphine as the Lewis base has a direct influence on the stability and structure of (FluTMS)2Ge(Cl)GeCl, leading to the formation of FluTMSGeCl·PEt3 as a stable product. Subsequent investigations of Ge(FluTMS)2 with a metastable Ge(I)Br solution show that at a ratio of 6:1 GeBr/Ge(FluTMS)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.