Ligand effects on electronic structure and bonding in U(III) coordination complexes: a combined MCD, EPR and...

Area of Science:

• Coordination Chemistry
• Uranium Chemistry
• Spectroscopy

Background:

• Trivalent uranium exhibits unique reactivity, crucial for catalysis and isotope separation.
• Understanding uranium electronic structure is key to designing ligands for specific applications.
• Studies on U(IV), U(V), and U(VI) are extensive, but U(III) electronic structure remains less explored.

Purpose of the Study:

• To elucidate the effects of ligand perturbation on the electronic structure of uranium(III) complexes.
• To investigate the electronic ground state of a U(III) complex with a redox non-innocent ligand.
• To demonstrate the efficacy of combined experimental and theoretical approaches in U(III) chemistry.

Main Methods:

• Combined Magnetic Circular Dichroism (MCD) and Electron Paramagnetic Resonance (EPR) spectroscopy.
• Density Functional Theory (DFT) calculations.
• Multireference wavefunction calculations.

Main Results:

• Ligand environment changes caused only minor perturbations in the uranium electronic structure of the studied U(III) complexes.
• The electronic ground state of a U(III) complex featuring a Bipy- ligand was redefined.
• The combined experimental and computational approach proved effective for evaluating U(III) electronic structure and bonding.

Conclusions:

• Minor ligand perturbations indicate challenges in significantly altering U(III) electronic structure and reactivity through ligand design.
• The study provides valuable insights into the electronic structure and bonding of U(III) complexes.
• This work highlights the utility of integrated spectroscopic and computational methods for advancing uranium coordination chemistry.