A very short uranium–uranium bond: The predicted metastable U22+
Abstract
Quantum chemical calculations, based on multiconfigurational wave functions and including relativistic effects, show that the U22+ system has a large number of low-lying electronic states with S of 0 to 2 and Λ ranging from zero to ten. These states share a very small bond length of about 2.30 Å, compared to 2.43 Å in neutral U2. The Coulomb explosion to 2 U+ lowers the energy by only 1.6 eV and is separated by a broad barrier.