C–H Functionalization Reactivity of a Nickel–Imide

Abstract

We report bifunctional reactivity of the β-diketiminato Ni­(III)–imide [Me₃NN]­NiNAd (<b>1</b>), which undergoes H-atom abstraction (HAA) reactions with benzylic substrates R–H (indane, ethylbenzene, toluene). Nickel–imide <b>1</b> competes with the nickel–amide HAA product [Me₃NN]­Ni–NHAd (<b>2</b>) for the resulting hydrocarbyl radical R^• to give the nickel–amide [Me₃NN]­Ni–N­(CHMePh)­Ad (<b>3</b>) (R–H = ethylbenzene) or aminoalkyl tautomer [Me₃NN]­Ni­(η²-CH­(Ph)­NHAd) (<b>4</b>) (R–H = toluene). A significant amount of functionalized amine R–NHAd is observed in the reaction of <b>1</b> with indane along with the dinickel imide {[Me₃NN]­Ni}₂(μ-NAd) (<b>5</b>). Kinetic and DFT analyses point to rate-limiting HAA from R–H by <b>1</b> to give R^•, which may add to either imide <b>1</b> or amide <b>2</b>, each featuring significant N-based radical character. Thus, these studies illustrate a fundamental competition possible in C–H amination systems that proceed via a HAA/radical rebound mechanism