Activation of Gas-Phase Uranyl: From an Oxo to a Nitrido Complex

The uranyl moiety, UO22+; is ubiquitous in the chemistry of uranium, the most prevalent actinide. Replacing the strong uranium-oxygen bonds in uranyl with other ligands is very challenging, having met with only limited success. We report here uranyl oxo bond activation in the gas phase to form a terminal nitrido complex, a previously elusive transformation. Collision induced dissociation of gas-phase UO2(NCO)Cl-2(-) in an ion trap produced the nitrido oxo complex, NUOCl2-, and CO2. NUOCl2- was computed by DFT to have C-s symmetry and a singlet ground state. The computed bond length and order indicate a triple U-N bond. Endothermic activation of UO2(NCO)Cl-2(-) to produce NUOCl2- and neutral CO2 was computed to be thermodynamically more favorable than NCO ligand loss. Complete reaction pathways for the CO2 elimination process were computed at the DFT level.