Mechanistic implications of an asymmetric intermediate in catalytic C–C coupling by a dinuclear nickel complex

Abstract

An asymmetric nickel–nickel bonded intermediate was isolated in the reaction of biphenylene with bis(1,5-cyclooctadiene)nickel and i-Pr₃P, where three of the four carbons are σ-bonded to one nickel. Mechanistic investigations support reactivity as a formal Ni(III)–Ni(I) complex; reductive elimination of cis-disposed Ni–C bonds from a single nickel centre directly provides a dinuclear Ni(I)–Ni(I) complex, a reaction relevant to dinuclear catalysis.