Assembly of One to Four As-4 Analogues, (Ge2As2)(2-) or (Ge3As)(3-), in the Coordination Sphere of [PhM](+), [MesM](+), or M2+ (M=Zn, Cd, Hg)

Pseudo-tetrahedral units of p-block atoms proved to be excellent building blocks for novel molecular architectures and for introducing new elemental combinations which are not otherwise accessible. In this work, we present a series of clusters obtained by reactions of binary Ge/As anions with [MPh2] (M=Zn, Cd, Hg; Ph=phenyl). The study is grounded on the fact that the binary reactant gained by extracting the solid 'K2GeAs' with ethane-1,2-diamine (en) co-exists as (Ge2As2)(2-) and (Ge3As)(3-) in solution. This allows for a larger variety of products by 'selecting' the most suitable species for the final ternary complex to crystallize. The reactions afforded the unprecedented first step of the corresponding interaction, thus attachment of (MPh)(+) to a pseudo-tetrahedral unit in [PhZn(Ge3As)](2-) (1) and [PhHg(Ge3As)](2-) (2), and complex anions with two, three, or four units, [(Ge3As)Zn(Ge2As2)](3-) (3), [Cd-3(Ge3As)(3)](3-) (4), and [Zn-3(Ge3As)(4)](6-) (5). Quantum chemistry confirmed the compositions and the positions of the Ge or As atoms, beside explaining structural peculiarities. The subtle impact of different [MR2] reactants was additionally studied by corresponding reactions using [ZnMes(2)] (Mes=mesityl), which showed success in selectively crystallizing [MesZn(Ge3As)](2-) (6). Based on our findings, we derive a suggestion of the underlying reaction cascade.