N-Heterocyclic Carbene Coinage Metal Complexes of the Germanium-Rich Metalloid Clusters [Ge(9)R(3)](−) and [Ge(9)R(I)(2)](2−) with R = Si((i)Pr)(3) and R(I) = Si(TMS)(3)

We report on the synthesis of novel coinage metal NHC (N-heterocyclic carbene) compounds of the germanium-rich metalloid clusters [Ge(9)R(3)](−) and [Ge(9)R(I)(2)](2−) with R = Si((i)Pr)(3) and R(I) = Si(TMS)(3). NHC(Dipp)Cu{η(3)-Ge(9)R(3)} with R = Si((i)Pr)(3) (1) represents a less bulky silyl group-substituted derivative of the known analogous compounds with R = Si((i)Bu)(3) or Si(TMS)(3). The coordination of the [NHC(Dipp)Cu](+) moiety to the cluster unit occurs via one triangular face of the tri-capped trigonal prismatic [Ge(9)] cluster. Furthermore, a series of novel Zintl cluster coinage metal NHC compounds of the type (NHCM)(2){η(3)-Ge(9)R(I)(2)} (R(I) = Si(TMS)(3) M = Cu, Ag and Au; NHC = NHC(Dipp) or NHC(Mes)) is presented. These novel compounds represent a new class of neutral dinuclear Zintl cluster coinage metal NHC compounds, which are obtained either by the stepwise reaction of a suspension of K(12)Ge(17) with Si(TMS)(3)Cl and the coinage metal carbene complexes NHCMCl (M = Cu, Ag, Au), or via a homogenous reaction using the preformed bis-silylated cluster K(2)[Ge(9)(Si(TMS)(3))(2)] and the corresponding NHCMCl (M = Cu, Ag, Au) complex. The molecular structures of NHC(Dipp)Cu{η(3)-Ge(9)(Si((i)Pr)(3))(3)} (1) and (NHC(Dipp)Cu)(2){η(3)-Ge(9)(Si(TMS)(3))(2)} (2) were determined by single crystal X-ray diffraction methods. In 2, the coordination of the [NHC(Dipp)Cu](+) moieties to the cluster unit takes place via both open triangular faces of the [Ge(9)] entity. Furthermore, all compounds were characterized by means of NMR spectroscopy ((1)H, (13)C, (29)Si) and ESI-MS.