Controlled cluster expansion at a Zintl cluster surface.

Reaction of the tris-hypersilyl nonagermanide Zintl cluster salt, K[Ge (Hyp) ] (Hyp=Si(SiMe ) ) with [Rh(η ,η -L)Cl] (L=1,5-cyclooctadiene, COD; norbornadiene, NBD) afforded eleven- and twelve-vertex homo-multimetallic clusters by cluster core expansion. Using a stepwise procedure, starting from the Zintl cluster [Rh(COD){Ge (Hyp) }] and [Ir(COD)Cl] , this methodology was expanded for the synthesis of eleven-vertex hetero-multimetallic clusters. A mechanism for the formation of these first examples of closo eleven-vertex Zintl clusters is proposed, informed by density functional theory calculations.