Tris(pentafluoroethyl)germane: Deprotonation and Hydrogermylation Reactions

Owing to the highly electron-withdrawing C₂ F₅ groups, the tris(pentafluoroethyl)germane (C₂ F₅ )₃ GeH represents an interesting Brønsted acidic compound. The germane is accessible by the treatment of the corresponding halogenogermanes (C₂ F₅ )₃ GeX (X=Cl, Br) with Bu₃ SnH. After clarifying its molecular structure in the solid state by X-ray diffraction, the acidity of (C₂ F₅ )₃ GeH was examined by treatment with different bases, for example, 1,8-bis(dimethylamino)naphthalene. The resulting germanate(II) ion [Ge(C₂ F₅ )₃ ]^- serves as a germyl group transfer reagent. The reaction with main-group and transition-metal complexes or organohalides opens access to a variety of different compounds, the structures of which were mostly determined by X-ray diffraction. The corresponding tricarbonylnickelate(0) complex [(CO)₃ NiGe(C₂ F₅ )₃ ]^- also gives information about the π-acceptor properties of the [Ge(C₂ F₅ )₃ ]^- ligand. Furthermore, hydrogermylation reactions of (C₂ F₅ )₃ GeH with alkynes afforded different stereoisomers (α,β-cis, β-trans) depending on the respective reaction conditions and substrates.