Electron-transfer-catalyzed rearrangement of unsymmetrically substituted diiron dithiolate complexes related to the active site of the [FeFe]-hydrogenases

Article abstract of DOI:10.1021/ic701327w

Novel asymmetrically substituted azadithiolate compounds [Fe ₂(CO)₄(κ²-dppe){μ-SCH ₂N(R)CH₂S}] (R = ⁱPr, 1a; CH₂CH ₂OCH₃, 1b; CH₂C₆H₅, 1c) have been synthesized by treatment of [Fe₂(CO)₆(μ-adt)] [adt = SCH₂N(R)CH₂S, with R = ⁱPr, CH ₂CH₂OCH₃, CH₂C₆H ₅] with dppe (dppe = Ph₂PCH₂CH ₂PPh₂) in refluxing toluene in the presence of Me ₃NO. 1a-c have been characterized by single-crystal X-ray diffraction analyses. The electrochemical investigation of 1a-c and of [Fe ₂(CO)₄(κ²-dppe)(μ-pdt)] (1d) [pdt = S(CH₂)₃S] in MeCN- and THF-[NBu₄][PF ₆] has demonstrated that the electrochemical reduction of 1a-d gives rise to an Electron-transfer-catalyzed (ETC) isomerization to the symmetrical isomers 2a-d where the dppe ligand bridges the iron centers. Compounds 2a-d were characterized by IR and NMR spectroscopy, elemental analysis, and X-ray crystallography for 2a.