Title: Oxo-Functionalization and Reduction of the Uranyl Ion Through Lanthanide-Element Bond Homolysis; Synthetic, Structural, and Bonding Analysis of a Series of Singly Reduced Uranyl Rare Earth 5f1-4fn Complexes
Authors: ARNOLD Polly L.HOLLIS EmmalinaNICHOL Gary S.LOVE Jason B.GRIVEAU Jean-ChristopheCACIUFFO RobertoMAGNANI NicolaMARON LaurentCASTRO LudovicYAHIA AhmedODOH Samuel OSCHRECKENBACH Georg
Citation: JOURNAL OF THE AMERICAN CHEMICAL SOCIETY vol. 135 no. 10 p. 3841−3854
Publisher: AMER CHEMICAL SOC
Publication Year: 2013
JRC N°: JRC81343
ISSN: 0002-7863
URI: http://pubs.acs.org/doi/abs/10.1021/ja308993g
http://publications.jrc.ec.europa.eu/repository/handle/JRC81343
DOI: 10.1021/ja308993g
Type: Articles in periodicals and books
Abstract: The heterobimetallic complexes [{UO2Ln-(py)2(L)}2], combining a singly reduced uranyl cation and a rare-earth trication in a binucleating polypyrrole Schiff-base macrocycle (Pacman) and bridged through a uranyl oxo-group, have been prepared for Ln = Sc, Y, Ce, Sm, Eu, Gd, Dy, Er, Yb, and Lu. These compounds are formed by the single-electron reduction of the Pacman uranyl complex [UO2(py)(H2L)] by the rare-earth complexes LnIII(A)3 (A = N(SiMe3)2, OC6H3But 2-2,6) via homolysis of a Ln−A bond. The complexes are dimeric through mutual uranyl exo-oxo coordination but can be cleaved to form the trimetallic, monouranyl “ate” complexes [(py)3LiOUO(μ-X)Ln(py)(L)] by the addition of lithium halides. X-ray crystallographic structural characterization of many examples reveals very similar features for monomeric and dimeric series, the dimers containing an asymmetric U2O2 diamond core with shorter uranyl U=O distances than in the monomeric complexes. The synthesis by LnIII−A homolysis allows [5f1-4fn]2 and Li[5f1-4fn] complexes with oxobridged metal cations to be made for all possible 4fn configurations. Variable-temperature SQUID magnetometry and IR, NIR, and EPR spectroscopies on the complexes are utilized to provide a basis for the better understanding of the electronic structure of f-block complexes and their f-electron exchange interactions. Furthermore, the structures, calculated by restricted-core or allelectron methods, are compared along with the proposed mechanism of formation of the complexes. A strong antiferromagnetic coupling between the metal centers, mediated by the oxo groups, exists in the UVSmIII monomer, whereas the dimeric UVDyIII complex was found to show magnetic bistability at 3 K, a property required for the development of single-molecule magnets.
JRC Directorate:Nuclear Safety and Security

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