Oxidative addition of Si–H bonds to metal-decorated Zintl clusters [Hyp₃Ge₉Ir(CO)PR₃] (R = Ph, ^<i>p</i>tolyl, Me)

Catalytic reactions with metalated Zintl clusters as catalysts represent a growing research field, whereby the concept of heterogeneous single-site catalysis is transferred towards homogeneous reactions, leading to so-called single-site homogeneous catalysts (SSHoCs). A synthetic protocol for three cluster compounds [Hyp₃Ge₉Ir(CO)PR₃] (Hyp = Si{SiMe₃}₃; R = Ph, ^<i>p</i>tolyl, Me; 1-3) is presented, in which the iridium atom is embedded in the polyhedral cluster surface. The products are characterized by NMR, IR and LIFDI/MS and also structurally characterized for R = Ph by single crystal X-ray structure determination, revealing a <i>closo</i>-[Ge₉Ir] cluster. The exchange of the phosphine ligand of 1 in solution, which is regarded as an important step to create the active site, is investigated for various phosphines. In subsequent reactions, oxidative addition of Si-H bonds of primary and secondary silanes SiHR₂R' (R/R' = H/Ph, H/^<i>p</i>MePh, H/^<i>p</i>{OMe}Ph, H/^<i>p</i>{NMe₂}Ph, and Ph/H) to the Ir atom is investigated. The addition reaction is directly monitored by NMR spectroscopy. Additionally, LIFDI/MS, IR spectroscopy, and single crystal structure determination of the addition products confirm the reaction. X-ray photoelectron spectroscopy (XPS) reveals that the transition metal atom and the Ge atoms of the supporting cluster have a low oxidation state.