Non-innocent bma ligand in a dissymetrically disubstituted diiron dithiolate related to the active site of the [FeFe] hydrogenases

The purpose of the present study was to evaluate the use of a non-innocent ligand as a surrogate of the anchored [4Fe4S] cubane in a synthetic mimic of the [FeFe] hydrogenase active site. Reaction of 2,3-bis(diphenylphosphino) maleic anhydride (bma) with [Fe2(CO)6(µ-pdt)] (propanedithiolate, pdt = S(CH2)3 S) in the presence of Me3NO-2H2O afforded the monosubstituted derivative [Fe2(CO)5(Me2NCH2PPh2)(µ-pdt)] (1). This results from the decomposition of the bma ligand and the apparent C–H bond cleavage in the released trimethylamine. Reaction under photolytic conditions afforded [Fe2(CO)4(bma)(µ-pdt)] (2). Compounds 1 and 2 were characterized by IR, NMR and X-ray diffraction. Voltammetric study indicated that the primary reduction of 2 is centered on the bma ligand.

Reaction of bma with [Fe2(CO)6(µ-pdt)] afforded [Fe2(CO)4(bma)(µ-pdt)]. Voltammetry indicated that the primary reduction is centered on the non-innocent bma ligand.Figure optionsDownload as PowerPoint slide