A mono-oxo-bridged binuclear iron(iii) complex with a Fe-O-Fe angle of 180.0 degrees and its catalytic activity for hydrogen evolution

There are potential applications for binuclear oxo-bridged iron complexes in biological processes, catalysts, and magnetic materials, and the design of new bridged-iron complexes is important. A new mono-oxo-bridged binuclear iron(iii) complex, [(H₂O)(bpc)Fe-O-Fe(bpc)(H₂O)], is designed and provided by the reaction of FeCl₃ with 1,2-bis(pyridine-2-carboxamido)-4,5-dichlorobenzene) (H₂bpc) in our group. Structural investigations show that two ions are connected with a Fe-O-Fe angle of 180.0 degrees, so it is a novel linear mono-oxo-bridged iron complex. Magnetic studies indicate that the iron(iii) ions are in low spin (ls) states. Electrochemical investigations exhibit that [(H₂O)(bpc)Fe-O-Fe(bpc)(H₂O)] has Fe-IV/III, Fe-III/II, and Fe-II/I couples at 0.689, -0.476, and -2.065 V versus Ag/AgNO₃, respectively, and can electro-catalyze hydrogen evolution from acetic acid with a rate constant of 7561.95 M^-1 s^-1. (authors)