Endohedral [Au@In ₁₀ ] ^9– Cluster: Synthesis and Characterization of Na _{3+ <i>x</i>} <i>A</i> _{6– <i>x</i>} In ₁₀ Au ( <i>x</i> = 0, 0.25; <i>A</i> = Rb, Cs)

The synthesis and characterization of two new compounds Na₃Rb₆In₁₀Au and Na_3.25Cs_5.75In₁₀Au 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- <i>Zintl-</i>type clusters. Dissolution experiments in liquid ammonia were carried out, revealing In₂Au as the reaction product.