Superatom-assembled boranes, carboranes, and low-dimensional boron nanomaterials based on aromatic icosahedral B₁₂ and C₂B₁₀

Using the experimentally known aromatic icosahedral superatoms I_h B₁₂H₁₂²⁻ and D_5d 1,12-C₂B₁₀H₁₂ as building blocks and based on extensive density functional theory calculations, we predict herein a series of core–shell superpolyhedral boranes and carboranes in a bottom-up approach, including the high-symmetry T_h B₁₂@B₁₅₂H₇₂²⁻ (2), C_2h C₂B₁₀@B₁₅₂H₇₂ (3), D_3d B₁₂@B₁₄₄H₆₆ (4), I_h B₁₂@C₂₄B₁₂₀H₇₂²⁻ (6), and D_5d C₂B₁₀@C₂₄B₁₂₀H₇₂ (7). More interestingly, the superatom-assembled linear D_2h B₃₆H₃₂²⁻ (8), close-packed planar D_3d B₈₄H₆₀²⁻ (10), and nearly close-packed core−shell D_3d B₁₂@B₁₄₄H₆₆ (4) can be extended periodically to form the one-dimensional (1D) α-rhombohedral borane nanowire B₁₂H₁₀ (Pmmm) (9), two-dimensional (2D) α-rhombohedral monolayer borophane B₁₂H₆ (P $\overline{3}$m1) (11), and the experimentally known three-dimensional (3D) α-rhombohedral boron (R $\overline{3}$m) (12) which can be viewed as an assembly of the monolayer B₁₂H₆ (11) staggered in vertical direction, setting up a bottom-up strategy to form low-dimensional boron-based nanomaterials from their borane “seeds” via partial or complete dehydrogenations. Detailed bonding analyses indicate that the high stability of these nanostructures originates from the spherical aromaticity of their icosahedral B₁₂ or C₂B₁₀ structural units which possess the universal skeleton electronic configuration of 1S²1P⁶1D¹⁰1F⁸ following the Wade’s n+1 rule. The infrared (IR) and Raman spectra of the most-concerned neutral B₁₂@B₁₄₄H₆₆ (4) and C₂B₁₀@C₂₄B₁₂₀H₇₂ (7) are computationally simulated to facilitate their experimental characterizations.