LAUSR

Abstract The nickel(II) pincer complex, [NiCl(PhPNP)] (PhPNP = anion of 2,5-bis(diphenylphosphinomethyl)pyrrole), has been employed as a precatalyst for the Suzuki-Miyaura cross-coupling reaction of aryl halides and boronic acids. Both electron-rich and electron-deficient aromatic bromides were found to undergo coupling with boronic acids in modest yield at elevated temperature in the presence of K3PO4·H2O. Preliminary mechanistic studies of the reaction identified a novel species formulated as the boronate complex, [Ni(OB{OH}{2-tolyl})(PhPNP)], which most likely represents a catalyst deactivation pathway. The productive catalytic cycle was found to be most consistent with a Ni(I)/Ni(III) process where the boronic acid serves as both reductant and nucleophile in the presence of base.