Binding of noble gas atoms by superhalogens

Because of their closed shells, noble gas (Ng) atoms (Ng = Ne, Ar, Kr, and Xe) seldom take part in chemical reactions, yet finding such mechanisms not only is of scientific interest but also has practical significance. Following a recent work by Mayer et al. [Proc. Natl. Acad. Sci. U. S. A. 116, 8167-8172 (2019)] on the room temperature binding of Ar to a superelectrophilic boron site embedded in a negative ion complex, B₁₂(CN)₁₁ ^-, we have systematically studied the effect of cluster size and terminal ligands on the interaction of Ng by focusing on B₁₂X₁₁(Ng) (X = H, CN, and BO) and B₁₂X₁₀(Ng)₂ (X = CN and BO) whose stabilities are governed by the Wade-Mingos rule and on C₅BX₅(Ng) (X = H, F, and CN) and C₄B₂(CN)₄(Ng)₂ whose stabilities are governed by the Huckel's aromaticity rule. Our conclusion, based on density functional theory, is that both the cluster size and the terminal ligands matter-the interaction between the cluster and the Ng atoms becomes stronger with increasing cluster size and the electron affinity of the terminal ligands. Our studies also led to a counter-intuitive finding-removing multiple terminal ligands can enable electrophilic centers to bind multiple Ng atoms simultaneously without compromising their binding strength.