Atomically precise clusters are important for understanding structure–property relationships of bulk materials. Here we report clusters of the general formula [K(2,2,2-cryptand)]₂[(μ₅-Cp*RE)₆(μ₆-κ³:κ³:κ³-Te₃)(μ-κ²:κ²-Te₂)(μ₃-η₂:κ:κ¹-Te₂)(μ₃-Te)₃] (Cp*, pentamethylcyclopentadienyl; RE = Y, Gd, Tb, Ho, Er). They are potential precursors to rare-earth tellurides, a class of topical quantum materials with interesting thermoelectric, magnetic, semiconducting and charge density wave properties. Crystallographic analyses reveal a common trigonal antiprismatic core of RE₆Te₁₀ with six RE atoms supported by three different types of tellurido ligands, namely Te^2–, Te₂^2– dianions, and a previously unknown tri-tellurido ligand Te₃^4–, upon which the six RE atoms are hinged into a pseudo-D_3d arrangement. Density functional theory studies reveal that the linear hypervalent Te₃^4– ion has the electronic structure characteristics of a three-centre, four-electron bond. Studies by ultraviolet–visible–near infrared spectroscopy and theoretical analyses suggest that these clusters are semiconductors with comparable band gaps to those of monocrystalline silicon and gallium arsenide.

原子精确的团簇对于理解散装材料的结构-性能关系非常重要。在这里，我们报道了通式 [K(2,2,2-cryptand)] ₂ [(μ ₅ -Cp*RE) ₆ (μ ₆ -κ ³ :κ ³ :κ ³ -Te ₃ )(μ- κ ² :κ ² -Te ₂ )(μ ₃ -η ₂ :κ:κ ¹ -Te ₂ )(μ ₃ -Te) ₃ ] (Cp*, 五甲基环戊二烯基；RE = Y、Gd、Tb、Ho、Er) 。它们是稀土碲化物的潜在前体，稀土碲化物是一类具有有趣的热电、磁性、半导体和电荷密度波特性的热门量子材料。晶体学分析揭示了 RE ₆ Te ₁₀的常见三角反棱柱核，其中六个 RE 原子由三种不同类型的碲配体（即 Te ^2–、Te ₂ ^2–二价阴离子）和先前未知的三碲配体 Te ₃ ^4–支撑，六个 RE 原子铰接成伪D _3d排列。密度泛函理论研究表明，线性超价Te ₃ ^4-离子具有三中心、四电子键的电子结构特征。紫外-可见-近红外光谱研究和理论分析表明，这些团簇是具有与单晶硅和砷化镓相当的带隙的半导体。