Electrochemical Behaviors of Pincer-Type NNN-Fe Complex and Catalytic H2 Evolution Activity

Abstract

We describe electrochemical reactivity of a pincer-type [NNN-Fe(tBuNC)3](ClO4)2 complex. Upon electron-reduction, the Fe(I) species experienced disproportionation to Fe(0) and Fe(II). The electron-reduced Fe center dissociated a tBuNC ligand to make an open coordination site, where a proton could be transferred. The low-spin Fe center, assisted by isocyanide and a pyridine-based NNN-pincer ligand, catalyzed efficiently the proton reduction reaction. Also, a Lewis basic amine site in the side ‘arm’ of NNN-pincer ligand lowered the free energy for the protonation of Fe center during the proton reduction process. DFT calculation provided insight into a plausible catalytic pathway.