New theoretical insights into high-coordination-number complexes in actinides-centered borane

Area of Science:

• Inorganic Chemistry
• Materials Science
• Quantum Chemistry

Background:

• Element coordination number influences chemical behavior and material properties.
• Understanding actinide chemistry is crucial for developing new materials but remains challenging.

Purpose of the Study:

• To report a new record high coordination number (CN) for actinides.
• To investigate the structural and electronic properties of actinide borane complexes.
• To provide insights for experimental synthesis of high-coordination actinide complexes.

Main Methods:

• Relativistic quantum chemistry methods were employed.
• Computational analysis of U(BH)n (n = 1 to 24) to confirm geometric minima.
• Global searches to identify stable structures for AnB24 and An(BH)24.

Main Results:

• A new record high coordination number for actinides was established in cage-like An(BH)24 structures.
• BH ligands were confirmed to be in the first shell around uranium in U(BH)n.
• Low CN half-cage structures were found for AnB24, prevailing over cage isomers.
• Intrinsic geometric differences arise from B sp3 hybridization and An 5f6d7s-B 2pz orbital interactions.

Conclusions:

• The study establishes a new benchmark for actinide coordination numbers.
• Findings provide valuable insights for experimentalists seeking to synthesize isolable high-coordination actinide complexes.
• A novel structural motif for boron clusters and nanostructures has been detailed.