Di-iron dithiolato complexes with 3-bromothiophene moiety: Preparation, structures, and electrochemistry

Abstract

A series of 3-bromothiophene-functionalized di-iron dithiolato complexes was reported. The starting complex [Fe2(CO)6{μ-SCH2CH(CH2OH)S}] (1) reacted with 3-bromothiophene-2-carboxylic acid promoting by N,N’-dicyclohexylcarbodiimide and 4-dimethylaminopyridine to yield the corresponding ester [Fe2(CO)6{μ-SCH2CHCH2O2C(3-C4H2SBr)S}] (2) in 91.4% yield. The phosphine-containing analogues [Fe2(CO)5L{μ-SCH2CHCH2O2C(3-C4H2SBr)S}] (L = PPh3, 3; P(4-C6H4Cl)3, 4; P(4-C6H4CF3)3, 5; P(C6H11)3, 6) were further obtained by the CO-exchange of 2 with the corresponding phosphine ligands and Me3NO∙2H2O in 68.0–76.7% yields. The new complexes 2–6 have been structurally identified by elemental analysis, spectroscopies, and particularly for 2–4 by X-ray crystallography. Additionally, the electrochemical and electrocatalytic properties of these products have been explored by cyclic voltammetry, which is showing that they can catalyze the reduction of protons to H2 by adding an acetic acid as a proton source into MeCN solution.