Imidazole-Containing (N3S)-NiII Complexes Relating to Nickel Containing Biomolecules

Abstract

Dimeric (N₂S)Ni complexes and the monomeric N₂S₂ bismercaptodiazacycloheptane nickel complex, (bme-dach)Ni, serve as precursors to two N₂-, N′-/ S- complexes where N₂ = diazacycloheptane, N′ = imidazole and S = thiolate. As rare examples of nickel complexes containing a mixed thiolate/imidazole ligand set, these complexes are characterized by X-ray diffraction, UV/vis, and variable temperature ¹H NMR spectroscopies, and electrochemistry. Density functional theory computations relate the orientation of the imidazole with respect to the N₂N′SNi square plane to the VT NMR observed fluxionality and activation parameters. The superoxide dismutase activity of the imidazole complexes was investigated by the nitroblue tetrazolium assay.