Transition-metal doping induces dramatic structural changes and leads to earlier planar / tubular / spherical / core–shell-like structural transitions in boron clusters. Inspired by the newly discovered spherical trihedral metallo-borospherene D3h La3&B18- (1) (Chen, et al., Nat. Commun., 2020, 11, 2766) and based on extensive first-principles theory calculations, we predict herein the first and smallest core– shell-like metallo-borospherenes C2v La3&[B2@B17]- (2) and D3h La3&[B2@B18]-(3) which contain a transition-metal-like B2 core at the cage center with unique donor–acceptor duality in La3&Bn-spherical trihedral shells (n = 17, 18). Detailed energy decomposition and bonding analyses indicate that the B2 core in these novel complexes serves as a p-donor in the equatorial direction mainly to coordinate three La atoms on the waist and a π/σ-acceptor in the axial direction mainly coordinated by two B6 triangles on the top and bottom. These highly stable core–shell complexes appear to be spherically aromatic in nature in bonding patterns. The IR, Raman, and photoelectron spectra of 2 and 3 are computationally simulated to facilitate their spectroscopic characterizations.
