Electronic Structures and Properties of Actinide‐Bimetal Compounds An₂O₂ (An=Th to Cf) and U₂E₂ (E=N, F, S)

Abstract

In this study, we investigated the geometry structure and the chemical bonding of actinide clusters An 2 O 2 by quantum chemistry calculations. Through the geometry searching for An 2 O 2 clusters with the combination of considerable initial structures and spin states, it is found that a novel ground-state structure of quasi-linear type for Pa 2 O 2 compares with a rhombic structure for the rest of An 2 O 2 clusters. Due to the more extended 5 f orbitals, the PaÀ Pa bond is verified to be a triple bond by the electronic configuration and the bond order analysis, which brings the quasi-linear structure of Pa 2 O 2 and distinguishes it from the rhombic ones. For both kinds of ground-state structures, the participation of 5 f orbitals in the AnÀ O bonds stabilizes the structures further. Owing to spinorbit coupling, the ground-state structure of U 2 O 2 changes from the linear one at the SR level to the rhombic one with SO into consideration. Further investigations on clusters U 2 E 2 with different ligands reveal that the quasi-linear U 2 F 2 has an equivalent quadruple bond. The decline of the bonding electrons of the UÀ U bond, the foremost causes for the change of the structures and illustrates the decrease of the UÀ U bond strength. Our investigations on An 2 O 2 and U 2 E 2 compounds provide some insights into the role of 5 f orbital in the chemical bonding of actinide compounds and f-f bonding in multiple bonding.

Multiconfigurational actinide nitrides assisted by double Möbius aromaticity

“…2a, in accordance with previous experimental and computational ndings. 30,67 Furthermore, we observed a noteworthy resemblance between the geometry of U 2 N 2 and the double Möbius aromatic species Pa 2 B 2 , where the total 16 valence electrons form four identical localized Pa-B covalent bonds, two delocalized s bonds and two delocalized p bonds. For the neutral U 2 N 2 with 22 valence electrons, we anticipate that 16 valence electrons engage in the same bonding pattern as Pa 2 B 2 , while the remaining 6 electrons are localized on two uranium atoms.…”

“…For the neutral U 2 N 2 with 22 valence electrons, we anticipate that 16 valence electrons engage in the same bonding pattern as Pa 2 B 2 , while the remaining 6 electrons are localized on two uranium atoms. The ground state of U 2 N 2 is predicted to be a septet 30 or quintet 67 at the DFT level, but experimental observations indicate that antiferromagnetic U 2 N 2 nitrides should have a singlet ground state. 29,68 This discrepancy may arise from the multiconfigurational nature of U 2 N 2 .…”

“…The ground state of U 2 N 2 is predicted to be a septet 30 or quintet 67 at the DFT level, but experimental observations indicate that antiferromagnetic U 2 N 2 nitrides should have a singlet ground state. 29,68 This discrepancy may arise from the multi-congurational nature of U 2 N 2 .…”