[Ba 4 @Sn 56 ] 36- as a Main-Group Second-Order Superatom. Interpenetrated Dodecahedrons as a Three-Dimensional Cluster-of-Clusters Structure.

Superatomic clusters are relevant species to further understanding of bonding and structural properties of atomically precise molecular nanoparticles. Here, we explore the characteristics of ligand-free [Ba 4 @Sn 56 ] 36- Zintl-ion, as a three-dimensional aggregate of clusters featuring four fused Ba@Sn 19 building units as an extension of the understanding in linear and cyclic superatomic cluster arrays. We provide a rational picture of the electronic shell in [Ba 4 @Sn 56 ] 36- as a cluster-of-clusters motif through the recently introduced second-order superatom approach, as a three-dimensional aggregation of superatomic clusters where their shells are able to interact. The electronic structure features both tangential and radial shells from the four building Ba@Sn 19 units, leading to a set of 1S' 2 1P' 6 1D' 10 1F' 14 and higher angular momentum shells and a second set of 2S' 2 2P' 6 2D' 10 2F' 14 2 G ' 8 second-order shells. Thus, the current approach serves to encourage the rationalization of molecular materials conceived from cluster building blocks toward a rational guide for synthetic efforts.