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

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 Ni^II–Ni^IIIintermediate with a Ni–Ni bond order of zero. The discrete Ni^II–Ni^IIIoxidation 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.