Tri-substituted Ge9 cluster mono-anions [Ge9{Si(SiMe3)3}3]− (1) were rationally synthesized by reacting acetonitrile suspension of the intermetallic precursor compound K4Ge9 with Si(SiMe3)3Cl. They were structurally characterized in [K(2,2,2-crypt)][Ge9{Si(SiMe3)3}3]. The Ge9-core of the anion is a tricapped trigonal prism with exo-bonded capping atoms. Reacting further a benzene suspension/oversaturated solution of 1 with organo-tin halides (SnR3X) led to the formation of the neutral tetra-substituted clusters [Ge9{Si(SiMe3)3}3{SnR3}] (2, R = phenyl; 3, R = n-butyl). In the structure of 2, the tin atom is found bonded to one of the six equivalent Ge atoms, while in 3 it is found above one of the triangular bases of the prism interacting with one or more Ge atoms in three crystallographically different molecules in the structure. Another reaction of acetonitrile solution of 1 with EtBr produced [Ge9{Si(SiMe3)3}3Et] (4) in which the ethyl group is exo-bonded to one of the six available Ge atoms with the Ge-C bond positioned radially to the Ge9 core. NMR spectroscopy indicates that all three neutral compounds (2, 3 and 4) are dynamic in solution at room temperature. Variable-temperature 1H NMR studies suggest that the process is intramolecular and solvent-independent. Reactions of 1 with other transition metal and main-group compounds led to more neutral species including [{R3Ge9}Cu{Ge9R3}{Cu(PPh3)}] (5) and [Ge9TlR3] (6), where R = Si(SiMe3)3. Variable-Temperature NMR studies of 6 indicate that it is dynamic and the process involves dissociation of the Tl+ ion from the molecule.

Functionalization of nine-atom deltahedral germanium clusters

249th National Meeting (2015)

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