Ag8(PEt3)6[Ge9(Hyp)2]4: Insight into the Formation Mechanism of the Intermetalloid Cluster Ag12[Ge9(Hyp)2]6

Recently we could demonstrate that the reaction of the bissilylated metalloid cluster K2[Ge9(Hyp)2] (Hyp = Si(SiMe3)3) with phosphine-stabilized silver chlorides gives the intermetalloid cluster Ag12[Ge9(Hyp)2]6, featuring a silver core of twelve silver atoms surrounded by six [Ge9(Hyp)2] units. Thereby, the silver atoms in the core appear to have an oxidation state of less than +I, indicating that a redox chemistry also takes place during the formation. We now present a possible precursor or intermediate to the intermetalloid cluster in this reaction system with the formula Ag8(PEt3)6[Ge9(Hyp)2]4. In this compound only four [Ge9(Hyp)2] units are arranged in a plane and connected via eight silver atoms. This compound seems to contain only silver cations, shedding further light on the complex solution and coordination chemistry of [Ge9(Hyp)2]2− with transition metal cations. As the intermetalloid cluster Ag12[Ge9(Hyp)2]6 can be obtained from dissolved crystals of Ag8(PEt3)6[Ge9(Hyp)2]4, this indicated that the Ag8 compound might be an intermediate (kinetic product) on the way to the Ag12 compound (thermodynamic product).