Ni complexes of N2S ligands with amine/imine and amine/amide donors with relevance to the active site of Ni superoxide dismutase

Abstract

A series of Ni complexes of the form [Ni((NNS)-S-Im)(RS)] ((NNS)-S-Im = (2-(N-(dimethylaminoethyl)iminomethyl) benzenethiolate; R = phenyl, 4-nitrophenyl, 4-fluorophenyl, 4-chlorophenyl, 4-t-butylphenyl, t-butyl), as well as two complexes of the form [Ni((NNS)-S-Am)(RS)] ((NNS)-S-Am = 2-(N-(dimethylaminoethyl) aminocarbonyl) benzenethiolate; R = phenyl, 4-nitrophenyl) have been synthesized using 2,2'-dithiodibenzaldehyde and 2,2'-dithiodibenzoylchloride, respectively, as synthons for introducing the thiolate into the tridentate ligands. The two ligands and series of complexes feature the N2S2 coordination environment found at the active site of Ni superoxide dismutase and differ only in the identity of one of the N donors (imine vs. amide). Those with the amide N donor contain the exact donor set present in reduced Ni superoxide dismutase. The complexes have been characterized by X-ray crystallography, electronic spectroscopy, and electrochemistry.