Reactions of U⁺with H₂, D₂, and HD Studied by Guided Ion Beam Tandem Mass Spectrometry and Theory

The kinetic energy-dependent reactions of the atomic actinide uranium cation (U+) with H2, D2, and HD were examined by guided ion beam tandem mass spectrometry. An average 0 K bond dissociation energy D0(U+ – H) = 2.48 ± 0.06 eV is obtained analysis endothermic product cross sections. Quantum chemistry calculations performed for comparison experimental thermochemistry, including high-level CASSCF–CASPT2–RASSI spin–orbit corrections. CCSD(T) CASSCF levels show excellent agreement experiment, whereas B3LYP PBE0 slightly overestimate M06 approach badly underestimates UH+. Theory was also used to investigate electronic structures reaction intermediates potential surfaces. branching ratio U+ indicates that these occur primarily via a direct mechanism, despite presence deep-well UH2+ formation according theory. reactivity hydride are compared those transition metal, lanthanide, cations, periodic trends discussed. These comparisons suggest 5f electrons on largely core uninvolved in reactive chemistry.