Endohedral Au@In109– Cluster: Synthesis and Characterization of Na3+xA6–xIn10Au (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@In109– 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@In109– Zintl-type clusters. Dissolution experiments in liquid ammonia were carried out, revealing In2Au as the reaction product.