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鈥揜are Earth 5f1
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- 作者：Polly L. Arnold ; Emmalina Hollis ; Gary S. Nichol ; Jason B. Love ; Jean-Christophe Griveau ; Roberto Caciuffo ; Nicola Magnani ; Laurent Maron ; Ludovic Castro ; Ahmed Yahia ; Samuel O. Odoh ; Georg Schreckenbach
- 刊名：The Journal of the American Chemical Society
- 出版年：2013
- 出版时间：March 13, 2013
- 年：2013
- 卷：135
- 期：10
- 页码：3841-3854
- 全文大小：669K
- 年卷期：v.135,no.10(March 13, 2013)
- ISSN：1520-5126
文摘
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, OC6H3But2-2,6) via homolysis of a Ln鈥揂 bond. The complexes are dimeric through mutual uranyl exo-oxo coordination but can be cleaved to form the trimetallic, monouranyl 鈥渁te鈥?complexes [(py)3LiOUO(渭-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鈺怬 distances than in the monomeric complexes. The synthesis by LnIII鈥揂 homolysis allows [5f1-4fn]2 and Li[5f1-4fn] complexes with oxo-bridged 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 all-electron 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.