Endohedral [Au@In ₁₀ ] ⁹– Cluster: Synthesis and Characterization of Na 3+ x A 6– x In ₁₀ Au ( x = 0, 0.25; A = Rb, Cs)

The synthesis and characterization of two new compounds Na₃Rb₆In₁₀Au and Na3.25Cs5.75In₁₀Au are reported, which contain [Au@In₁₀]⁹⁻ clusters as anionic entities. Single-crystal X-ray structure analysis shows that the alkali metal composition is the key factor for structure formation, while the anionic entity remains unchanged. The chemical composition was confirmed by SEM/EDS measurements, and the given compositions of both compounds are fixed according to the line compounds. Quantum chemical calculations for the compound Na₃Rb₆In₁₀Au were performed and show a band gap at the Fermi level, classifying the materials as salt-like, including endohedral [Au@In₁₀]⁹⁻ Zintl-type clusters. Dissolution experiments in liquid ammonia were carried out, revealing In₂Au as the reaction product.