Structural and Theoretical Assessment of Covalency in a Pu(III) Borohydride Complex

Area of Science:

• Inorganic Chemistry
• Actinide Chemistry
• Organometallic Chemistry

Background:

• Actinide borohydride complexes have been known for over 80 years.
• Structural validation of plutonium borohydride complexes using single-crystal X-ray diffraction (XRD) has been lacking.

Purpose of the Study:

• To report the first structurally validated plutonium borohydride complex.
• To investigate the electronic structure and bonding in actinide borohydride complexes.

Main Methods:

• Single-crystal X-ray diffraction (XRD) for structural determination.
• Nuclear Magnetic Resonance (NMR) spectroscopy for characterization.
• Density Functional Theory (DFT), Energy Decomposition Analysis (EDA), and Quantum Theory of Atoms in Molecules (QTAIM) for theoretical calculations.

Main Results:

• The first plutonium(III) borohydride complex, Pu2(H3BPnBu2BH3)6, was synthesized and structurally characterized by XRD and NMR spectroscopy.
• Theoretical calculations and experimental data on metal-boron distances indicate a general trend of decreasing metal-borohydride covalency in M2(H3BPnBu2BH3)6 complexes: M = U(III) > Pu(III) > Ln(III).

Conclusions:

• This work provides the first definitive structural evidence for a plutonium borohydride complex.
• The findings contribute to understanding the nature of bonding and electronic properties within actinide borohydride systems and establish a benchmark for future studies.