N−N Bond Forming Reductive Elimination via a Mixed-Valent Nickel(II)-Nickel(III) Intermediate

• Published in: Angewandte Chemie (International ed.) Vol. 55; no. 26; pp. 7534 - 7538
• Main Authors: Diccianni, Justin B., Hu, Chunhua, Diao, Tianning
• Format: Journal Article
• Language: English
• Published: Germany Blackwell Publishing Ltd 20.06.2016; Wiley Subscription Services, Inc
• Edition: International ed. in English
• Subjects: Biological activity; Catalysis; Ductile brittle transition; Forming; Fracture mechanics; Metal bonding; Metal-metal bonding; Metals; mixed-valent compounds; Natural products; Nickel; N−N bond formation; Oxidation; reductive elimination; Valence; N−N bond formation; nickel; reductive elimination; metal-metal bonding; mixed-valent compounds
• ISSN: 1433-7851; 1521-3773
• DOI: 10.1002/anie.201602566

Natural products containing N–N bonds exhibit important biological activity. Current methods for constructing N−N bonds have limited scope. An advanced understanding of the fundamental N−N bond formation/cleavage processes occurring at the transition‐metal center would facilitate the development of catalytic reactions. Herein we present an N−N bond‐forming reductive elimination, which proceeds via a mixed‐valent NiII–NiIII intermediate with a Ni–Ni bond order of zero. The discrete NiII–NiIII oxidation states contrast with the cationic dimeric Ni analogue, in which both Ni centers are equivalent with an oxidation state of 2.5. The electronic structures of these mixed‐valent complexes have implications for the fundamental understanding of metal–metal bonding interactions. A “paddle‐wheel” Ni complex undergoes N−N bond forming reductive elimination under oxidative conditions. The intermediate is a mixed‐valent NiII–NiIII complex with a Ni–Ni bond order of zero.