On the Origins of Faster Oxo Exchange for Uranyl(V) versus Plutonyl(V)

Activation of uranyl(V) oxo bonds in the gas phase is demonstrated by reaction of U16O2 + with H2 18O to produce U16O18O+ and U18O2 +. In contrast, neptunyl(V) and plutonyl(V) are comparatively inert toward exchange. Computed potential energy profiles (PEPs) reveal a lower yl oxo exchange transition...

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Bibliographic Details
Published in:Journal of the American Chemical Society 2012-09, Vol.134 (37), p.15488-15496
Main Authors: Rios, Daniel, del Carmen Michelini, Maria, Lucena, Ana F, Marçalo, Joaquim, Gibson, John K
Format: Article
Language:English
Subjects:
Oxygen - chemistry
Plutonium - chemistry
Uranium - chemistry
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Summary:Activation of uranyl(V) oxo bonds in the gas phase is demonstrated by reaction of U16O2 + with H2 18O to produce U16O18O+ and U18O2 +. In contrast, neptunyl(V) and plutonyl(V) are comparatively inert toward exchange. Computed potential energy profiles (PEPs) reveal a lower yl oxo exchange transition state for uranyl(V)/water as compared with neptunyl(V)/water and plutonyl(V)/water. A correspondence between oxo exchange rates in gas phase and acid solutions is apparent; the contrasting oxo exchange rates of UO2 + and PuO2 + are considered in the context of covalent bonding in actinyls. Hydroxo exchange of U16O2(16OH)+ with H2 18O to give U16O2(18OH)+ proceeded much faster than oxo exchange, in accord with a lower computed transition state for OH exchange. The PEP for the addition of H2O to UO2 + suggests that both UO2 +·(H2O) and UO(OH)2 + should be considered as potential products.
ISSN:0002-7863
1520-5126
DOI:10.1021/ja305800q