Synthesis and catalytic activity of nickel(II) complexes containing NCN pincer ligands

In this study, nickel(II) complexes [LmeNi(II)Cl]+(BPh4)−, [LmeNi(II)Cl]+(PF6)− and [Let2Ni(II)]+(BPh4)−2 were synthesised and characterized in the solution and solid states. Ligands Lme (C11H12N6) and Let (C13H17N6) featured a central carbene donor linked to pendant pyrazoles via either methylene or ethylene linkers. The catalytic activity of all three complexes was tested in the Kumada cross coupling reaction between phenylmagnesium bromide and aromatic halogen substituted substrates. [LmeNi(II)Cl]+(BPh4)−was found to be the most active catalyst.