Volume 95 Issue 49 | p. 11 | Concentrates
Issue Date: December 18, 2017

Uranium doubles up as a catalyst

Chemists develop a metal complex that provides the best evidence yet for reversible two-electron redox properties in an f-block element
Department: Science & Technology
News Channels: Organic SCENE
Keywords: Catalysis, uranium, redox
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This dimeric uranium(V) complex, joined at the center by azobenzene, provides the best evidence yet for transition-metal redox behavior in an f-block element.
Credit: Courtesy of Stephen Liddle
A ball-and-stick structure shows a uranium imido complex that undergoes two-electron redox reactions.
 
This dimeric uranium(V) complex, joined at the center by azobenzene, provides the best evidence yet for transition-metal redox behavior in an f-block element.
Credit: Courtesy of Stephen Liddle

Reversible, two-electron redox processes in which a substrate is added and subsequently eliminated from a transition metal are a defining feature of most catalytic cycles. This behavior is typically unheard of, though, when it comes to lanthanide and actinide metals. The f-block metals are used as catalysts, but they tend to exhibit irreversible one- or multielectron oxidation or reduction steps, and the complete redox sequence hasn’t been observed in one reaction system. Researchers led by Stephen T. Liddle of the University of Manchester and Laurent Maron of the University of Toulouse have now found evidence that a uranium complex can satisfy all the criteria of classical single-metal, two-electron oxidative addition-reductive elimination, and they make a case that uranium can mimic traditional transition-metal catalysis (Nat. Commun. 2017, DOI: 10.1038/s41467-017-01363-0). The researchers added azobenzene to a uranium(III) triamide complex they previously reported to form a dimeric uranium(V) imido complex, which readily expels azobenzene back out upon heating. The researchers confirmed the oxidation and reduction steps using a combination of structural, spectroscopic, magnetic, and computational studies. The reaction sequence is not yet optimized, Liddle says, but the findings provide a pathway to discovering new lanthanide and actinide catalysts—for example, to synthesize aniline derivatives.

 
Chemical & Engineering News
ISSN 0009-2347
Copyright © American Chemical Society

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