Ruthenium Decorated Tris-Silylated Germanium Zintl Clusters Featuring an Unexpected Ligand Arrangement

The incorporation of transition metal atoms into [Ge₉] clusters is a widely studied area of Zintl-cluster chemistry. Recently, it was shown that clusters comprising single transition metal atoms in the cluster surface show catalytic properties. Here, we present a synthetic approach to four new compounds comprising silylated Ge₉ clusters with organometallic ruthenium complexes. [η⁵-Ge₉Hyp₃]RuCp* (1), [η¹-Ge₉(SiBu₂H)₃]RuCp(PPh₃)₂ (2), and [Hyp₃Ge₉][RuCp(PPh₃)₂(MeCN)] (3b) (Cp = cyclopentadienyl, Cp* = pentamethylcyclopentadienyl, Hyp = Si(SiMe₃)₃, Ph = C₆H₅, Bu = tert-butyl) were characterized by means of NMR spectroscopy and single-crystal structure determination. In the case of 2, a new isomer with an approximated C₄ symmetric monocapped square antiprism of nine Ge atoms with an unexpected ligand arrangement comprising three ditertbutylsilane ligands attached to the open square was obtained. [Hyp₃Ge₉][RuCp(PPh₃)₂] (3a) was characterized via NMR spectroscopy and LIFDI mass spectrometry. Overall, we were able to show that the steric demand of the ligands Cp vs. Cp* and hypersilylchloride vs. ditertbutylsilane strongly influence the arrangement of the atoms and ligands on the cluster. In addition, the solvent also affects the cluster, as it appears that the ruthenium atom in 3a dissociates from the cluster surface upon acetonitrile coordination to form 3b. These results show that choosing the right synthetic tools and ligands makes a big difference in the outcome of the metalation reaction.