[PtZn2Ge18(Hyp)8] (Hyp = Si(SiMe3)3): A Neutral Polynuclear Chain Compound with Ge9(Hyp)3 Units

The reaction of [ZnGe18­(Hyp)6] (Hyp = Si­(SiMe3)3) with Pt­(PPh3)4 gives the neutral polynuclear complex of Ge9(Hyp)3 units [HypZn–Ge9(Hyp)3–Pt–Ge9(Hyp)3–ZnHyp], 1. Within 1, the central Pt atom is bound η3 to both Ge9(Hyp)3 units to which further ZnHyp units are bound again, symmetric η3, to the other side of the Ge9(Hyp)3 units, leading to the longest chain compound exhibiting Ge9(Hyp)3 units that is known to date. Dissolved crystals of 1 give a violet solution, showing an absorption maximum around 543 nm. Further UV–vis investigations on different M x Ge9(Hyp)3 compounds show that the absorption maximum depends on the number of transition metal atoms bound to the Ge9(Hyp)3 unit, which is supported by TD-DFT calculations.