Sc@B(28)(−), Ti@B(28), V@B(28)(+), and V@B(29)(2−): Spherically Aromatic Endohedral Seashell-like Metallo-Borospherenes

Transition-metal-doped boron nanoclusters exhibit unique structures and bonding in chemistry. Using the experimentally observed seashell-like borospherenes C(2) B(28)(−/0) and C(s) B(29)(−) as ligands and based on extensive first-principles theory calculations, we predict herein a series of novel transition-metal-centered endohedral seashell-like metallo-borospherenes C(2) Sc@B(28)(−) (1), C(2) Ti@B(28) (2), C(2) V@B(28)(+) (3), and C(s) V@B(29)(2−) (4) which, as the global minima of the complex systems, turn out to be the boron analogues of dibenzenechromium D(6h) Cr(C(6)H(6))(2) with two B(12) ligands on the top and bottom interconnected by four or five corner boron atoms on the waist and one transition-metal “pearl” sandwiched at the center in between. Detailed molecular orbital, adaptive natural density partitioning (AdNDP), and iso−chemical shielding surface (ICSS) analyses indicate that, similar to Cr(C(6)H(6))(2), these endohedral seashell-like complexes follow the 18-electron rule in bonding patterns (1S(2)1P(6)1D(10)), rendering spherical aromaticity and extra stability to the systems.