Electrocatalytic Azide Oxidation Mediated by a Rh(PNP) Pincer Complex

Christophe Rebreyend; Yann Gloaguen; Martin Lutz; Jarl Ivar van der Vlugt; Inke Siewert; Sven Schneider; Bas de Bruin

doi:10.1002/chem.201702938

Electrocatalytic Azide Oxidation Mediated by a Rh(PNP) Pincer Complex

Chemistry. 2017 Dec 11;23(69):17438-17443. doi: 10.1002/chem.201702938. Epub 2017 Oct 12.

Authors

Christophe Rebreyend¹, Yann Gloaguen¹, Martin Lutz², Jarl Ivar van der Vlugt¹, Inke Siewert³, Sven Schneider³, Bas de Bruin¹

Affiliations

¹ Homogeneous and Supramolecular Catalysis van't Hoff Institute for Molecular Sciences (HIMS), University of Amsterdam, Amsterdam, The Netherlands.
² Crystal and Structural Chemistry, Bijvoet Center for Biomolecular Research, Utrecht University, Padualaan 8, 3584 CH, Utrecht, The Netherlands.
³ Universität Göttingen, Institut für Anorganische Chemie, Tammannstr. 4, 37077, Göttingen, Germany.

Abstract

One-electron oxidation of the rhodium(I) azido complex [Rh(N₃ )(PNP)] (5), bearing the neutral, pyridine-based PNP ligand 2,6-bis(di-tert-butylphosphinomethyl)pyridine, leads to instantaneous and selective formation of the mononuclear rhodium(I) dinitrogen complex [Rh(N₂ )(PNP)]⁺ (9⁺ ). Interestingly, complex 5 also acts as a catalyst for electrochemical N₃^- oxidation (E_p ≈-0.23 V vs. Fc^+/0 ) in the presence of excess azide. This is of potential relevance for the design of azide-based and direct ammonia fuel cells, expelling only harmless dinitrogen as an exhaust gas.

Keywords: EPR spectroscopy; dinitrogen complexes; fuel cells; nitrido; rhodium.