The design and the synthesis of cluster compounds have been actively investigated by many research groups over the past decades owing to the specific electronic properties and reactivities of such compounds, and thus their potential use for innovative materials.1 Binary main group element aggregates with elemental combinations E14/E16, E14/E15, or E13/E15 proved to be useful precursors for multinary (semi-)metal clusters or network structures of the general type [MxE13/14yE15/16z]q–, or their organo-functionalized derivatives [Mx(RE14)yE16z] (M = (transition) metal, R = functional organic ligand).2-3 Treatment of the binary precursors with further metal compounds afforded cluster anions like [Ta@Ge8As6]3–, [(Bi6)Zn3(TlBi5)]4–, [Co2@Sn5Sb7]3–, or [Ge24Sn36Se132]24–, which exhibit very unusual geometric and electronic structures.4-10 The attachment of organic groups to the inorganic cluster cores further manipulates their chemical and physical properties, in some cases creating unprecedented non-linear optical properties, such as recently found for [(StySn)4S6] (Sty = 4–(CH2=CH)–C6H4).11 We investigate formation mechanisms, reactivities, and physical properties of these uncommon compounds in order to advance their controlled design and application.