B111, B112, B113, and B114: The most stable core-shell borospherenes with an icosahedral B12 core at the center exhibiting superatomic behaviors

Boron allotropes are known to be predominately constructed by icosahedral B12 cages, while icosahedral-B12 stuffing proves to effectively improve the stability of fullerene-like boron nanoclusters in the size range between B98–B102. However, the thermodynamically most stable core-shell borospherenes with a B12 icosahedron at the center still remains unknown. Based on the structural motif of D5h C70 and extensive first-principles theory calculations, we predict herein the high-symmetry C5v B111+ (3) which satisfies the Wade’s n+1 and n+2 skeletal electron counting rules exactly and the approximately electron sufficient Cs B111 (4), Cs B112 (5), Cs B113 (6), and Cs B114 (7) which are the most stable neutral core-shell borospherenes with a B12 icosahedron at the center reported to date in the size range between B68–B130, with Cs B112 (5) being the thermodynamically most favorite species in the series. Detailed orbital and bonding analyses indicate that these spherically aromatic species all contain a negatively charged icosahedral B122− core at the center which exhibits typical superatomic behaviors in the electronic configuration of 1S21P61D101F8, with its dangling valences saturated by twelve radial B-B 2c-2e σ bonds between the B12 inner core and the B70 outer shell. The infrared (IR) and Raman spectra of the concerned species are computationally simulated to facilitate their future characterizations.