Synthesis, characterization and electrochemistry of dinuclear iron complexes with SNC donors

Abstract

The three-component reactions of PhNHC(S)OR, Et3N and Fe3(CO)12 in THF at 0 °C afford the [Et3NH]+ salt of the [(μ-PhNCOR)Fe2(CO)6(μ-S)]− cluster anion (R = CH3, CH2Ph). The S-centered cluster anion reacts with CH3I to give (μ-k2N,C-PhNCOR)Fe2(CO)6(μ-SCH3) (1, R = CH3; 3, R = CH2Ph) and (μ-k2N,C-PhNCOCH3)Fe2(CO)6(μ4-S)Fe2(CO)6(μ-SCH3) (2). Further reactions of 1 with 1 equiv of PPh2R in the presence of Me3NO lead to the corresponding monophosphine-substituted complexes (μ-k2N,C-PhNCOCH3)Fe2(CO)5(L)(μ-SCH3) (4, L = PPh3; 5, L = PPh2Py). Similarly, reactions of 3 with PPh2R produce the corresponding monophosphine-substituted complexes (μ-k2N,C-PhNCOCH2Ph)Fe2(CO)5(L)(μ-SCH3) (6, L = PPh3; 8, L = PPh2Py) besides an unexpected monophosphine-disubstituted complex (μ-k2N,C-PhNCOCH2Ph)Fe2(CO)4(PPh3)2(μ-SCH3) (7). All the new complexes have been characterized by elemental analyses, IR, 1H NMR, 13C NMR and 31P NMR spectroscopy and 1, 2 and 4–8 structurally determined by X-ray crystallography. Electrochemical studies indicate that when using HOAc or TFA as a proton source, complexes 1, 4–6 and 8 exhibit catalytic H2 production.