Direct C–C coupling of two Ni-salphen complexes to yield dinickel-disalphen complexes with symmetric and non-symmetric substitution-patterns

The synthesis of symmetric and non-symmetric 5,5′-linked disalophen Ni(II) complexes by the Suzuki-Miyaura-reaction is reported. Also, the synthesis and structural characterization of four Ni(II)-precursor complexes are presented. The 5-Br-substituted mononuclear complexes 4 and 5 are coupled to the pinacolborane substituted complexes 6 and 7 yielding the four dinuclear dinickel complexes 8–11 in good yields. The crystal structure of dinuclear complex 8 was obtained revealing a coplanar arrangement between the two salophen fragments. Electronic spectra as well as DFT-calculations on the ground states and excitation energies are reported and they reveal a small coupling between the electronically saturated Ni-salophen complexes.