ABSTRACT: Using the experimentally known aromatic icosahedral Ih B12H122- and C5v B11CH12- as building blocks and based on extensive density functional theory calculations, we present herein bottom-up approaches to form the superatomassembled two-dimensional (2D) few-layered α-
rhombohedral borophanes (B12)nH6 (α-1–5) and (B12)nH2 (α-6–10), γ-orthorhombic borophanes (B12-B2)nH8 (γ-1–5), and carborophanes (CB11-CBC)nH8 (σ-1–5) (n = 1–5) and experimentally known three-dimensional (3D) α-B12, γ-B28, and B4C crystals based on aromatic icosahedral B12 and CB11, with the B–B dumbbells in γ-1–5 and C–B–C chains in σ-1–5 serving as interstitial units to help stabilize the systems. As both chemically and mechanically stable species, the optimized 2D monolayer, bilayer, trilayer, tetralayer, and pentalayer borophanes and carborophanes all turn out to be semiconductors in nature, in particular, the few-layered carborophanes σ-3–5 ((CB11-CBC)nH8 (n = 3–5)) with the calculated band gaps of Egap = 1.32–1.26 eV appear to be well compatible with traditional silicon semiconductors in band gaps. Detailed adaptive natural density partitioning (AdNDP) bonding analyses indicate that both the icosahedral B12 and CB11 cages in these 2D and 3D crystal structures follow the universal superatomic electronic configuration of 1S21P61D101F8 matching the n + 1 Wade’s rule (n = 12), rendering local spherical aromaticity and overall high stability to the systems.
