Half-Sandwich LaBn(14-17)_2021

     Novel lanthanide boride complexes with unique structural and bonding patterns have been observed in recent experiments. Based on extensive first-principles theory calculations, we predict herein the possible existence of half-sandwich C2v LaB14- (1), C1 LaB15 (2), C5v LaB16- (3), and Cs LaB17 (4) which all contain a La center coordinated by a bowl-like Bn ligand (n = 14–17). Detailed bonding analyses indicate that effective d-p coordination interactions exist between the La center and Bn ligand, making these half-sandwich complexes p dually aromatic in nature. Energy decomposition analyses reveal that electrostatic (50.2%) and covalent (49.8%) interactions contribute almost equally to the overall attraction in LaB14- (1), with the La centre serving as both electron donor and acceptor. Molecular dynamics simulations show that both LaB14- (1) (La[B4B10] -) and LaB17 (4) (La[BB5B11]) with multicenter fluxional bonds behave like Wankel motors at finite temperatures.