The Role of Lithium Ions on the Solubility of KE in Ethylenediamine and the Oxidation of the Zintl Anions [E] (E = Ge, Sn, Pb) as well as [Ge].

Zintl phases are excellent precursors for nine atom [E] clusters, which are readily accessible by dissolution of AE phases (A = Na-Rb; E = Ge-Pb) in ethylenediamine (en). In contrast, the binary alkali-metal tetrel phases of composition AE are insoluble in en. Furthermore, Li cations are rarely investigated as counterions for tetrel element Zintl clusters. We report here that KE, comprising [E] polyanions (E = Ge, Sn, and Pb), which are insoluble in en, readily dissolves in en in the presence of lithium ions and the four atomic polyanions [E] are oxidized to nine-atom [E] clusters during dissolution. We isolated crystals of [Li(en)][Ge] and [Li(en)][E] (E = Sn and Pb) with exclusively Li counterions. Furthermore, the alkali-metal ion exchange of KGe with LiCl in en results also in the oxidation of [Ge] to [Ge-Ge] dimers which were isolated as partially and fully ion-exchanged salts such as K[Li(en)][Ge-Ge] and [Li(en)][Ge-Ge], respectively. NMR spectroscopic investigations of solutions of [Sn] that contain variable Li:K ratio reveal contact K/[Sn] ion pairs, while Li ions form solvent-separated ion pairs. The role of Li ions on the solubility of Zintl phases and Li assisted oxidation of Zintl ions is highlighted.