Oxidative addition of aryl electrophiles to a prototypical nickel(0) complex : mechanism and structure/reactivity relationships

Bajo, Sonia and Laidlaw, Gillian and Kennedy, Alan R. and Sproules, Stephen and Nelson, David J. (2017) Oxidative addition of aryl electrophiles to a prototypical nickel(0) complex : mechanism and structure/reactivity relationships. Organometallics, 36 (8). pp. 1662-1672. ISSN 0276-7333

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    Abstract

    Detailed kinetic studies of the reaction of a model Ni0 complex with a range of aryl electrophiles have been conducted. The reactions proceed via a fast ligand exchange pre-equilibrium, followed by oxidative addition to produce either [NiIX(dppf)] (and biaryl) or [NiII(Ar)X(dppf)]; the ortho substituent of the aryl halide determines selectivity between these possibilities. A reactivity scale is presented in which a range of substrates is quantitatively ranked in order of the rate at which they undergo oxidative addition. The rate of oxidative addition is loosely correlated to conversion in prototypical cross-coupling reactions. Substrates that lead to NiI products in kinetic experiments produce more homocoupling products under catalytic conditions.