N2 and O2 Cleavage by a Uranium(III) Complex

  • Author: Angewandte Chemie International Edition
  • Published Date: 23 September 2020
  • Source / Publisher: Angewandte Chemie International Edition/Wiley-VCH
  • Copyright: Wiley-VCH GmbH
thumbnail image: N<sub>2</sub> and O<sub>2</sub> Cleavage by a Uranium(III) Complex

Dinitrogen (N2) and dioxygen (O2) are the main components of air. The activation of N2 and O2 is an interesting challenge for chemists. The industrial conversion of N2 to ammonia, for example, is performed on a large scale using the Haber–Bosch process, but requires very high temperatures and pressures. Uranium-based materials can act as effective catalysts for ammonia production from N2, but the cleavage of N2 or O2 by molecular uranium compounds under mild conditions had not been accomplished so far.


Congqing Zhu, Nanjing University, China, and colleagues have developed the first example of N2 and O2 cleavage by a uranium(III) complex under ambient conditions without an external reducing agent. The complex, [N(CH2CH2NPiPr2)3U]2(TMEDA) (TMEDA = tetramethylethylenediamine), was synthesized via the reduction of the uranium(IV) complex [N(CH2CH2NPiPr2)3UCl] with potassium graphite (KC8) in the presence of TMEDA under argon.


The complex can react with dinitrogen to give [N(CH2CH2NPiPr2)2(CH2CH2NPiPr2N)U]2 (pictured). The hydrolysis of this product gives ammonia. The uranium(III) complex can also react with dioxygen to give [N(CH2CH2NPiPr2)2(CH2CH2NPiPr2O)U]2(μ-O)2. Both reactions proceed under mild conditions (1 atm N2 or O2, room temperature). The ligand is non-innocent, i.e., it takes part in the reaction: electrons for the reduction of N2 and O2 are provided by both U(III) and P(III) atoms. The N2 triple-bond breaking implies a six-electron reduction, while the O2 cleavage involves an eight-electron reduction of two O2 molecules (schematically pictured below).

 


 

 

Article Views: 2152

Sign in Area

Please sign in below

Additional Sign In options

Please note that to comment on an article you must be registered and logged in.
Registration is for free, you may already be registered to receive, e.g., the newsletter. When you register on this website, please ensure you view our terms and conditions. All comments are subject to moderation.

Article Comments - To add a comment please sign in

If you would like to reuse any content, in print or online, from ChemistryViews.org, please contact us first for permission. more

Follow on Facebook Follow on Twitter Follow on YouTube Follow on LinkedIn Follow on Instagram RSS Sign up for newsletters

Magazine of Chemistry Europe (16 European Chemical Societies) published by Wiley-VCH