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Title: Equatorial coordination of uranyl: Correlating ligand charge donation with the O yl-U-O yl asymmetric stretch frequency

In uranyl coordination complexes, UO 2(L) n 2+, uranium in the formally dipositive [O=U=O] 2+ moiety is coordinated by n neutral organic electron donor ligands, L. The extent of ligand electron donation, which results in partial reduction of uranyl and weakening of the U=O bonds, is revealed by the magnitude of the red-shift of the uranyl asymmetric stretch frequency, ν 3 . This phenomenon appears in gas-phase complexes in which uranyl is coordinated by electron donor ligands: the ν 3 red-shift increases as the number of ligands and their proton affinity (PA) increases. Because PA is a measure of the enthalpy change associated with a proton-ligand interaction, which is much stronger and of a different nature than metal ion-ligand bonding, it is not necessarily expected that ligand PAs should reliably predict uranyl-ligand bonding and the resulting ν 3 red-shift. In this study, ν 3 was measured for uranyl coordinated by ligands with a relatively broad range of PAs, revealing a surprisingly good correlation between PA and ν 3 frequency. From computed ν 3 frequencies for bare UO 2 cations and neutrals, it is inferred that the effective charge of uranyl in UO 2(L) n 2+ complexes can be reduced tomore » near zero upon ligation by sufficiently strong charge-donor ligands. The basis for the correlation between ν 3 and ligand PAs, as well as limitations and deviations from it, are considered. It is demonstrated that the correlation evidently extends to a ligand that exhibits polydentate metal ion coordination.« less
Authors:
ORCiD logo [1] ; ORCiD logo [2] ;  [3] ;  [4] ;  [4] ;  [5]
  1. Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States). Chemical Sciences Division
  2. Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States). Computational Research Division
  3. Duquesne Univ., Pittsburgh, PA (United States). Dept. of Chemistry and Biochemistry
  4. Radboud Univ., Nijmegen (Netherlands). Inst. for Molecules and Materials and FELIX Lab.
  5. Radboud Univ., Nijmegen (Netherlands). Inst. for Molecules and Materials and FELIX Lab.; Univ. of Amsterdam (Netherlands). Van‘t Hoff Inst. for Molecular Sciences (HIMS)
Publication Date:
Grant/Contract Number:
AC02-05CH11231; SC0016568; 724.011.002; AC05-00OR22725
Type:
Accepted Manuscript
Journal Name:
Journal of Organometallic Chemistry
Additional Journal Information:
Journal Volume: 857; Journal Issue: C; Journal ID: ISSN 0022-328X
Publisher:
Elsevier
Research Org:
Lawrence Berkeley National Laboratory (LBNL), Berkeley, CA (United States). National Energy Research Scientific Computing Center (NERSC); Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States). Oak Ridge Leadership Computing Facility (OLCF)
Sponsoring Org:
USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22). Scientific User Facilities Division; Duquesne Univ., Pittsburgh, PA (United States); Netherlands Organisation for Scientific Research (NWO); Innovative and Novel Computational Impact on Theory and Experiment (INCITE)
Country of Publication:
United States
Language:
English
Subject:
38 RADIATION CHEMISTRY, RADIOCHEMISTRY, AND NUCLEAR CHEMISTRY; Uranyl; Coordination complexes: gas-phase; IRMPD; Proton affinity
OSTI Identifier:
1436668