Perfect cubic La-doped boron clusters La6&[La@B24]+/0 as the embryos of low-dimensional lanthanide boride nanomaterials

Abstract

La-doped boron nanoclusters have received considerable attention due to their unique structures and bonding. Inspired by recent experimental observations of the inverse sandwich D_8h La₂B₈ (1) and triple-decker C_2v La₃B₁₄⁻ (2) and based on extensive global searches and first-principles theory investigations, we present herein the possibility of the perfect cubic La-doped boron clusters O_h La₆&[La@B₂₄]⁺ (3, ¹A_1g) and O_h La₆&[La@B₂₄] (4, ²A_2g) which appear to be the embryos of the metallic one-dimensional La₁₀B₃₂ (5) nanowire, two-dimensional La₃B₁₀ (6) nanosheet, and three-dimensional LaB₆ (7) nanocrystal, facilitating a bottom-up approach to build cubic lanthanide boride nanostructures from gas-phase clusters. Detailed molecular orbital and bonding analyses indicate that effective (d–p)σ, (d–p)π and (d–p)δ covalent coordination interactions exist in La₆&[La@B₂₄]^+/0 (3/4) clusters, while the 1D La₁₀B₃₂ (5), 2D La₃B₁₀ (6), and 3D LaB₆ (7) crystals exhibit mainly electrostatic interactions between the trivalent La centers and cubic B₂₄ frameworks, with weak but discernible coordination contributions from La (5d) ← B (2p) back-donations. The IR and Raman spectra of La₆&[La@B₂₄]^+/0 (3/4) and band structures of La₁₀B₃₂ (5) and La₃B₁₀ (6) are computationally simulated to facilitate their future characterizations.