Fajman Christian E, Dankert Dominik M, Klein Wilhelm, Fässler Thomas F
TUM School of Natural Sciences, Department Chemie, Technische Universität München, Lichtenbergstraße 4, Garching, Germany.
Catalysis Research Center, Technische Universität München, Ernst-Otto-Fischer-Straße 1, Garching, Germany.
Chemistry. 2025 May 8;31(26):e202500592. doi: 10.1002/chem.202500592. Epub 2025 Apr 8.
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.
津特耳相是制备九原子[E]簇合物的优良前驱体，通过将AE相（A = Na - Rb；E = Ge - Pb）溶解于乙二胺（en）中可轻松得到这些簇合物。相比之下，组成AE的二元碱金属四价元素相不溶于en。此外，锂离子作为四价元素津特耳簇合物的抗衡离子很少被研究。我们在此报告，由[E]聚阴离子（E = Ge、Sn和Pb）组成的KE不溶于en，但在锂离子存在下易溶于en，并且在溶解过程中四原子聚阴离子[E]被氧化为九原子[E]簇合物。我们分离出了仅含锂抗衡离子的[Li(en)][Ge]和[Li(en)][E]（E = Sn和Pb）晶体。此外，在en中KGe与LiCl进行碱金属离子交换也会使[Ge]氧化为[Ge - Ge]二聚体，分别以部分和完全离子交换盐的形式分离出来，如K[Li(en)][Ge - Ge]和[Li(en)][Ge - Ge]。对含有不同Li:K比例的[Sn]溶液进行核磁共振光谱研究，揭示了接触型K/[Sn]离子对，而锂离子形成溶剂分隔离子对。突出了锂离子在津特耳相溶解度以及锂离子辅助的津特耳离子氧化过程中的作用。
