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John K. Gibson, Richard G. Haire
Einsteinium chemistry in the gas phase: exploring the divalent character of heavy actinides
The first chemical studies of the monopositive einsteinium ion, Es+, in the gas phase have been carried out, and its behavior compared to those for other actinide ions, with a particular focus on Bk+. The yield of laser-ablated EsO+ indicates that the Es+-O bond energy is significantly smaller than that of Bk+-O. Fluorination of Es+ and Bk+ through F-abstraction from hexafluoropropene demonstrated clearly the stability of the divalent state of Es: whereas by this process both BkF+ and BkF2+ are produced, only the "divalent" EsF+ product is formed. The reaction of Es+ with several different alkenes produced only small yields of adducts ( e.g., EsC4H8+). These adducts are the first organoeinsteinium complexes to be identified. Whereas Es+ was inert towards 1,5-cyclooctadiene, in contrast Bk+ dehydrogenated this substrate to give BkC8H8+, demonstrating the greater activation activity of Bk+ than Es+ towards alkenes. The chemical behaviors observed in these studies are consistent with the predicted electronic structure and energetics of Es+, and the results obtained are discussed in the context of systematic trends across the actinide series.
Radiochimica Acta, Oldenbourg Wissenschaftsverlag
Print ISSN: 0033-8230
Volume: 91, 08/2003
Pages: 441