Transition-metal-doped boron clusters have received considerable attention in recent years. The experimentally observed planar or quasi-planar C2h B10(I), C2v B11-(II), C3v B12(III), and C2v B13+ (IV) are known to be boron analogs of benzene. Extensive global minimum searches and first-principles theory investigations performed herein indicate that doping these aromatic boron clusters with a nickel atom generates the closed-shell half-sandwich complexes C2v NiB10(1, 1A1), Cs NiB11-(2, 1A'), C3v NiB12(3, 1A1), and Cs NiB13+ (4, 1A') which are all well-defined global minima of the systems with the coordination numbers of CN = 10, 11, 12, and 13, respectively. Detailed bonding analyses indicate that these Ni-doped boron complexes are effectively stabilized by coordination interactions between the Ni center and aromatic Bn-/0/+ ligands (n = 10–13) and follow the universal coordination bonding pattern of r plus p double delocalization. Molecular dynamics simulations show that, among these complex clusters, NiB11-(2) behaves like a Wankel motor at room temperature with the B3 inner wheel rotating almost freely inside the quasi-rotating B8 outer bearing in a concerted mechanism, revealing typical bonding fluctuations/fluxionalities in a molecular motor due to thermal vibrations. The IR, Raman and electronic spectra of the concerned species are computationally simulated to facilitate their experimental characterizations.
