Self-organized Tetranickel(II) Molecular Square with Imidazolinyl-imidazole Bridging Ligand

A novel square-planar cyclic tetranuclear nickel(II) complex coordinated by im-H2bizn− ligand (Him-H2bizn = 4,5-bis(4,5-dihydro-1H-imidazol-2-yl)imidazole), [NiII4(im-H2bizn)4(MeOH)4(py)4](ClO4)4·2ether (py = pyridine), has been synthesized. The tetranickel(II) complex crystallized in C2/m space group and exhibited antiferromagnetic intramolecular coupling with J = −24 K. The complex arrests ClO4− ion by moderate O-H⋯O and weak multipoint C-H⋯O hydrogen bonds.