Synthesis and use of trans-dichlorido-tetrakis-(N-R-imidazole)nickel(II) complexes in Kumada–Tamao–Corriu cross-coupling reactions

Two dichlorido-tetrakis-(N-R-imidazole)nickel(II) complexes (R = 2,6-diisopropylphenyl (1); methyl (2)) have been synthesised. A single crystal X-ray diffraction study was carried out for 1, which revealed a centrosymmetric complex with the nickel centre placed in an octahedral coordination environment. Both complexes showed high activities (TOFs up to 60200 mol(ArBr) mol(Ni)−1 h−1) in Kumada–Tamao–Corriu cross-coupling of arylhalides with arylgrignards. No significant differences in activity were observed between the two complexes.

Graphical abstractTwo imidazole nickel(II) complexes of formula [NiCl2(imidazole)4] have been synthesised. As revealed by an X-ray structure analysis carried out for one of the complexes, the nickel atom sits in an octahedral coordination environment with the two chlorine atoms being positioned trans to each other. Both complexes turned out to be highly efficient in Kumada–Tamao–Corriu cross coupling of arylbromides with arylgrignards. The complexes could also be used with aryl chlorides.Figure optionsDownload full-size imageDownload as PowerPoint slideHighlights► First use of imidazole nickel complexes in Kumada–Tamao–Corriu cross coupling. ► TOFs up to 60200 mol(ArBr) mol(Ni)−1 h−1. ► NMR and X-ray studies reveal steric interactions between the imidazole ligands.