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

A combined anion photoelectron spectroscopic and relativistic coupled-cluster computational study of the electronic structure of the UN2 molecule is presented. Because the photoelectron spectrum of the uranium dinitride negative ion, UN2-, directly reflects the electronic structure of neutral UN2, we have measured and relied upon the photoelectron spectrum of the UN2- anion as a means of mapping the electronic structure of neutral UN2. In addition to the electron affinity of the UN2 ground state, energy levels of the UN2 excited states were well characterized by the close interplay between the experiment and high-level theory. We found that both electron attachment and electronic excitation significantly bend the UN2 molecule and elongate its U≡N bond. Implications for the activation of UN2 are discussed.