Synthesis and characterization of novel organonickel and organocobalt complexes via carbon–chlorine bond activation

The ortho-metalated nickel(II) complexes 3, 4, 7 and 8 were obtained by the reaction of ortho-halogeno aromatic bis-Schiff bases 1, 2, 5 and 6 with the stoichiometric amount of Ni(PMe3)4. The combination of 5 and 6 with two equivalents of Ni(PMe3)4 resulted in oxidative addition of the double C–Cl bonds to afford ortho-bis-chelated nickel(II) complexes 9 and 10. The reaction of 6 with Co(PMe3)4 gave rise to di-nuclear ortho-metalated cobalt(II) complex 12 through C–Cl bond activation while the reaction of 5 with Co(PMe3)4 delivered bis-chelated cobalt(I) complex 11 through both C–Cl and C–H bond activation. The structures of complexes 3, 4, 8, 9, 11 and 12 were determined by X-ray single crystal diffraction. The catalytic activity of bis-chelated cobalt(I) complex 11 as catalyst for C,C-coupling reaction was explored.