Theoretical Prediction of Divalent Actinide Borozene Complexes.

Area of Science:

• Inorganic Chemistry
• Theoretical Chemistry
• Materials Science

Background:

• The aromatic boron cluster B8(2-), termed 'borozene', stabilizes monovalent lanthanides in C7-LnB8- complexes.
• Low-valency actinide complexes are rare, and B8(2-) presents a potential stabilizing ligand.
• Previous studies focused on lanthanide complexes, leaving actinide stabilization by B8(2-) unexplored.

Purpose of the Study:

• To theoretically investigate actinide metal-doping of octa-boron clusters (AnB8, where An = Pa, U, Np, Pu).
• To determine the structural preferences and electronic properties of these novel actinide-boron complexes.
• To assess the stabilizing capability of the B8(2-) ligand for divalent actinides.

Main Methods:

• Density Functional Theory (DFT) calculations were employed to study AnB8 clusters.
• Structural optimization was performed to identify stable half-sandwich and chair-like configurations.
• Bonding analyses, including covalent interactions and aromaticity, were conducted.

Main Results:

• Both half-sandwich and chair-like structures were found for all AnB8 species.
• Half-sandwich structures are more stable for UB8, NpB8, and PuB8, forming M(II)[B8(2-)] complexes.
• The B8(2-) ligand exhibits σ and π double aromaticity, with strong An-B covalent bonds contributing to complex stability.

Conclusions:

• The B8(2-) ligand effectively stabilizes divalent actinides, forming An(II) borozene complexes.
• Covalent interactions between actinides and the B8(2-) cluster are crucial for complex stability.
• These findings expand the scope of borozene chemistry to low-valency actinides.