Sea-shell-like B 31 + and B 32 : two new axially chiral members of the borospherene family.

Since the discovery of the cage-like borospherenes D 2d B 40 -/0 and the first axially chiral borospherenes C 3 / C 2 B 39 - , a series of fullerene-like boron clusters in different charge states have been reported in theory. Based on extensive global minimum searches and first-principles theory calculations, we present herein two new axially chiral members C 2 B 31 + (I) and C 2 B 32 (VI) to the borospherene family. B 31 + (I) features two equivalent heptagons on the top and one octagon at the bottom on the cage surface, while B 32 (VI) possesses two equivalent heptagons on top and two equivalent heptagons at the bottom. Detailed bonding analyses show that both sea-shell-like B 31 + (I) and B 32 (VI) follow the universal σ + π double delocalization bonding pattern of the borospherene family, with ten delocalized π bonds over a σ skeleton, rendering spherical aromaticity to the systems. Extensive molecular dynamics simulations show that these novel borospherenes are kinetically stable below 1000 K. The IR, Raman, and UV-vis spectra of B 31 + (I) and B 32 (VI) are computationally simulated to facilitate their future experimental characterizations.