文摘
Inspired by recent experimental realizations of two-dimensional (2D) metals and alloys, we theoretically investigate plausible formation of new germanium frameworks based on the aggregation of ligand-decorated Ge9 clusters. Here, we explore the formation of single-, double-, and triply connected arrays of species with Zintl-ion core of Ge9 leading to the formation of dimers ([Ge9R2]22–), hexamers ([Ge9R]66–), and two-dimensional arrays ([M3{Ge9}3]∞; M = Li, Cs). This can be potentially addressed by the controlled removal of ligands from the [Ge9{Si(SiMe3)3}3]− monoanion acting as the source of Ge9 building blocks. Our results reveal that the bonding between different Ge9 cores is favorable and covalent in nature as a localized 2c–2e Ge–Ge exobond. The extended two-dimensional {Ge9}∞ array designed as [M3{Ge9}3]∞ with M = Li, Cs in periodic boundary conditions is energetically stable. The resulting layered Ge-structure has similar stability as that of germanene. It exhibits large pores with radius of 5.23 Å between the three-connected Ge9 clusters. Hence, it can be considered as a the first superatomic honeycomb structure proposed to date. This 2D material exhibit a small band gap in contrast to the 2D germanene which has no such gap. Hence, the two-dimensional Ge9 cluster-based compound would have potential for a tunable bandgap material. The use of Ge-clusters is suggested as an interesting approach to obtain nanomaterials accessing to novel alleotropes.
