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Title: Theoretical Study of Oxovanadium(IV) Complexation with Formamidoximate: Implications for the Design of Uranyl-Selective Adsorbents

Poly(acrylamidoxime) fibers are the current state of the art adsorbent for mining uranium from seawater. However, the competition between uranyl (UO 2 2+) and vanadium ions poses a challenge to mining on the industrial scale. In this work, we employ density functional theory (DFT) and coupled-cluster methods (CCSD(T)) in the restricted formalism to investigate potential binding motifs of the oxovanadium(IV) ion (VO 2+) with the formamidoximate ligand. Consistent with experimental EXAFS data, the hydrated six-coordinate complex is predicted to be preferred over the hydrated five-coordinate complex. Here, our investigation of formamidoximate-VO 2+ complexes universally identified the most stable binding motif formed by chelating a tautomerically rearranged imino hydroxylamine via the imino nitrogen and hydroxylamine oxygen. The alternative binding motifs for amidoxime chelation via a non-rearranged tautomer and 2 coordination are found to be ~11 kcal/mol less stable. Ultimately, the difference in the most stable VO 2+ and UO 2 2+ binding conformation has important implications for the design of more selective UO 2 2+ ligands.
 [1] ;  [2] ;  [3] ;  [4] ;  [2]
  1. Univ. of Tennessee, Knoxville, TN (United States). Dept. of Chemistry
  2. Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States). Chemical Sciences Division
  3. Georgia Inst. of Technology, Atlanta, GA (United States). Dept. of Environmental Engineering
  4. Univ. of Tennessee, Knoxville, TN (United States). Dept. of Chemistry; Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States). Chemical Sciences Division
Publication Date:
Grant/Contract Number:
AC05-00OR22725; AC02-05CH11231
Accepted Manuscript
Journal Name:
Industrial and Engineering Chemistry Research
Additional Journal Information:
Journal Volume: 55; Journal Issue: 15; Journal ID: ISSN 0888-5885
American Chemical Society (ACS)
Research Org:
Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
Sponsoring Org:
USDOE Office of Nuclear Energy (NE)
Country of Publication:
United States
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY; Oxovanadium (IV) ion; VO2+; amidoxime functional group; coordination motifs; density functional theory (DFT); coupled-cluster calculations (CCSD(T))
OSTI Identifier: