Mapping the Electronic Structure of the Uranium(VI) Dinitride Molecule, UN₂

Area of Science:

• Quantum Chemistry
• Spectroscopy
• Computational Chemistry

Background:

• Understanding the electronic structure of molecules is crucial for predicting their reactivity.
• Uranium-containing molecules, such as uranium dinitride (UN2), are of interest due to their unique chemical properties.
• Previous studies on UN2 have been limited, necessitating further investigation into its electronic configuration and bonding.

Purpose of the Study:

• To investigate the electronic structure of neutral uranium dinitride (UN2) and its negative ion (UN2-).
• To characterize the electron affinity and excited states of UN2.
• To explore the geometric changes in UN2 upon electron attachment and electronic excitation.

Main Methods:

• Anion photoelectron spectroscopy was employed to probe the electronic states of UN2-.
• Relativistic coupled-cluster computational methods were utilized to model the electronic structure of UN2 and UN2-.
• Experimental spectroscopic data was correlated with theoretical calculations to validate findings.

Main Results:

• The photoelectron spectrum of UN2- provided direct insights into the electronic structure of neutral UN2.
• The electron affinity of the UN2 ground state was determined.
• High-level theory and experimental data confirmed that both electron attachment and electronic excitation significantly bend the UN2 molecule and elongate the U≡N bond.

Conclusions:

• The study successfully mapped the electronic structure of UN2 by analyzing its anion's photoelectron spectrum.
• The findings reveal significant geometric distortions in UN2 upon electron attachment and excitation, impacting its reactivity.
• The results have implications for understanding and potentially controlling the activation of UN2 in chemical reactions.