Abstract
Although crown ethers can selectively bind many metal cations, little is known regarding the solution properties of crown ether complexes of the uranyl dication, UO22+. Here, the synthesis and characterization of isolable complexes in which the uranyl dication is bound in an 18-crown-6-like moiety are reported. A tailored macrocyclic ligand, templated with a Pt(II) center, captures UO22+ in the crown moiety, as demonstrated by results from single-crystal X-ray diffraction analysis. The U(V) oxidation state becomes accessible at a quite positive potential (E1/2) of −0.18 V vs Fc+/0 upon complexation, representing the most positive UVI/UV potential yet reported for the UO2n+ core. Isolation and characterization of the U(V) form of the crown complex are also reported here; there are no prior reports of reduced uranyl crown ether complexes, but U(V) is clearly stabilized by crown chelation. Joint computational studies show that the electronic structure of the U(V) form results in significant weakening of U-Ooxo bonding despite the quite positive reduction potential at which this species can be accessed, underscoring that crown-ligated uranyl species could demonstrate unique reactivity under only modestly reducing conditions.
| Original language | English |
|---|---|
| Pages (from-to) | 9597-9604 |
| Number of pages | 8 |
| Journal | Journal of the American Chemical Society |
| Volume | 146 |
| Issue number | 14 |
| DOIs | |
| State | Published - Apr 10 2024 |
Funding
Dedicated to Prof. Victor W. Day on the occasion of his 80th birthday. This work was supported by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences through the Early Career Research Program (DE-SC0019169). A.C.E. was supported by a U.S. National Science Foundation Research Traineeship (NRT) at the University of Kansas (DGE-1922649). M.Z.M. and V.A.G. were supported by ORNL’s Laboratory Directed Research and Development (LDRD) program. This research used resources of the National Energy Research Scientific Computing Center (NERSC), a U.S. Department of Energy Office of Science User Facility located at Lawrence Berkeley National Laboratory, operated under contract no. DE-AC02-05CH11231. Analytical data were obtained from the CENTC Elemental Analysis Facility at the University of Rochester, supported by the US National Science Foundation through award CHE-0650456. The authors thank Michael K. Takase (Beckman Institute, Caltech) for assistance with refinement of the structure of 2 obtained by single-crystal XRD analysis.