Electron‐Triggered Imine Coupling: Synthesis and Characterization of Three Redox States (0,–1,–2) of a Ni(N2S2) Complex

Abstract

AbstractMetal imine‐thiolate complexes, M(NS)2 are known to undergo imine C−C bond formation to give M(N2S2) complexes (M=Co, Ni) containing a redox‐active ligand. Although these transfor‐mations are not typically quantitative, we demonstrate here that the one‐electron reduction of a related Ni bis(imine‐thiolate) complex affords the corresponding paramagnetic [Ni(N2S2)]‐ anion (2⋅−) exclusively; subsequent oxidation with [Cp2Fe]BF4 then affords a high yield of neutral 2 (Cp=η5‐cyclopentadienyl). Moreover, electrochemical studies indicate that a second one‐electron reduction affords the diamagnetic dianion. Both anionic products were isolated and characterized by SC‐XRD and their electronic structures were investigated by UV‐vis spectro‐electrochemistry, EPR and NMR spectroscopy, and DFT studies. These studies show that reduction proceeds primarily on the ligand, with (N2S2)4− containing both thiolate and ring‐delocalized anions.