Nickel(II)‐Mediated Reversible Thiolate/Disulfide Conversion as a Mimic for a Key Step of the Catalytic Cycle of Methyl‐Coenzyme M Reductase

Abstract

According to the well‐accepted mechanism, methyl‐coenzyme M reductase (MCR) involves Ni‐mediated thiolate‐to‐disulfide conversion that sustains its catalytic cycle of methane formation in the energy saving pathways of methanotrophic microbes. Model complexes that illustrate Ni‐ion mediated reversible thiolate/disulfide transformation are unknown. In this paper we report the synthesis, crystal structure, spectroscopic properties and redox interconversions of a set of NiII complexes comprising a tridentate N2S donor thiol and its analogous N4S2 donor disulfide ligands. These complexes demonstrate reversible NiII‐thiolate/NiII‐disulfide (both bound and unbound disulfide‐S to NiII) transformations via thiyl and disulfide monoradical anions that resemble a primary step of MCR's catalytic cycle.

Bio-inspired, Multifunctional Metal–Thiolate Motif: From Electron Transfer to Sulfur Reactivity and Small-Molecule Activation

“…Additional studies involving other metals and sulfur ligands are thus required. In this vein, another Co system 26 and a Ni-based one displayingdisulfide/thiolate (inter)conversion have been recently described,27 demonstrating that such activity can be supported by a broad range of transition metal ions.…”