N-Heterocyclic Carbene Coinage Metal Complexes of the Germanium-Rich Metalloid Clusters [Ge₉R₃] and [Ge₉R₂]² with R = Si(Pr)₃ and R = Si(TMS)₃.

We report on the synthesis of novel coinage metal NHC (-heterocyclic carbene) compounds of the germanium-rich metalloid clusters [Ge₉R₃] and [Ge₉R₂]² with R = Si(Pr)₃ and R = Si(TMS)₃. NHCCu{η³Ge₉R₃} with R = Si(Pr)₃ () represents a less bulky silyl group-substituted derivative of the known analogous compounds with R = Si(Bu)₃ or Si(TMS)₃. The coordination of the [NHCCu]⁺ moiety to the cluster unit occurs via one triangular face of the tri-capped trigonal prismatic [Ge₉] cluster. Furthermore, a series of novel cluster coinage metal NHC compounds of the type (NHC)₂{η³Ge₉R₂} (R = Si(TMS)₃ = Cu, Ag and Au; NHC = NHC or NHC) is presented. These novel compounds represent a new class of neutral dinuclear cluster coinage metal NHC compounds, which are obtained either by the stepwise reaction of a suspension of KGe with Si(TMS)₃Cl and the coinage metal carbene complexes NHCCl ( = Cu, Ag, Au), or via a homogenous reaction using the preformed bis-silylated cluster K₂[Ge₉(Si(TMS)₃)₂] and the corresponding NHCCl ( = Cu, Ag, Au) complex. The molecular structures of NHCCu{η³Ge₉(Si(Pr)₃)₃} () and (NHCCu)₂{η³-Ge₉(Si(TMS)₃)₂} () were determined by single crystal X-ray diffraction methods. In , the coordination of the [NHCCu]⁺ moieties to the cluster unit takes place via both open triangular faces of the [Ge₉] entity. Furthermore, all compounds were characterized by means of NMR spectroscopy (¹H, C, Si) and ESI-MS.