Investigation on the Coordination Bonding Nature of Actinide-Doped Endohedral Borospherenes An@B (An = U, Np, Pu, Am, Cm).

Endohedral metallo-borospherenes M@B have received considerable attention since the discovery of B in 2014. However, the coordination bonding nature of most of actinide-doped endohedral An@B still remains in dispute or unexplored. Extensive and systematic first-principles theory calculations performed herein unveil the ground states of triplet U@B (, , A), quartet U@B (, , B), quintet Np@B (, , A), sextet Np@B (, , A), septet Pu@B (, , A), octet Am@B (, , A), and octet Cm@B (, , A) at the coupled-cluster with triple excitations CCSD(T) level. Detailed principal interacting spin orbital (PISO) and adaptive natural density partitioning (AdNDP) analyses reveal their coordination bonding patterns and show that, with the numbers of unpaired -electrons in parallel spins varying from n = 2, 3, 4, 5, 6, 7, to 7 in these complexes, the percentage contribution of the An 5f-involved PISO pairs to overall coordination bonding interactions decreases monotonously from 41% to 1%, and the contribution of An 6d-involved PISO pairs increases monotonously from 47% to 72%, while the marginal contribution of An 7s-involved PISO pairs remains basically unchanged (4~7%). The IR, Raman, and photoelectron spectra of the most concerned species are computationally simulated to facilitate their characterizations in future experiments.