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Abstract Developing a comprehensive understanding of the reactivity of uranium species remains an important goal in areas ranging from the development of nuclear fuel processing methods to studies of the… Click to show full abstract
Abstract Developing a comprehensive understanding of the reactivity of uranium species remains an important goal in areas ranging from the development of nuclear fuel processing methods to studies of the migration and fate of the element in the environment. Electrospray ionization (ESI) can provide relatively easy access to gas-phase complexes containing uranium in high oxidation states for subsequent studies of intrinsic structure and reactivity. We report here the formation of a superoxo- complex, [UVIO2(O2)(O2C-CF3)2]−, which is created by ESI using “gentle” conditions (low sheath gas flow rate and low desolvation temperature). CID of [UVIO2(O2)(O2C-CF3)2]− causes elimination of O2, presumably with concomitant reduction of UVIO22+ to UVO2+. Remarkably, subsequent CID of [UVO2(O2C-CF3)2]− creates a species at m/z 330, which is attributed to formation of [UVO(F)4]−. A similar species is generated by multiple-stage CID in a linear ion trap, and collision-cell CID in a Fourier-transform ion-cyclotron resonance (FT-ICR) mass spectrometer, when initiated with the tris-trifluoroacetato complex [UVIO2(O2C-CF3)3]−. High accuracy mass measurement using the FT-ICR instrument confirms the composition assignment for the species at m/z 330.