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 NaRbInAu and NaCsInAu are reported, which contain [Au@In] 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 NaRbInAu were performed and show a band gap at the Fermi level, classifying the materials as salt-like, including endohedral [Au@In] type clusters. Dissolution experiments in liquid ammonia were carried out, revealing InAu as the reaction product.