The development of efficient electrocatalysts for proton reduction(H_(2)production)based on earth-abundant metals is a scientific challenge with implications for energy storage and generation.Inspired by[FeFe]-hydroge...The development of efficient electrocatalysts for proton reduction(H_(2)production)based on earth-abundant metals is a scientific challenge with implications for energy storage and generation.Inspired by[FeFe]-hydrogenase enzymes,several compounds based on the{Fe_(2)Cp_(2)(CO)_(2)}framework have been investigated in this respect but,to date,only two charge-neutral derivatives,with a terminal cyanide and a bridging dimethylamino-(CNMe_(2)^(+))or methylthio-(CSMe^(+))carbyne ligand,were found to be effective electrocatalysts.Herein,we extended the investigation to related cationic derivatives with the cyanide ligand being replaced with various monodentate,hydrophilic N-P-or S-donor ligands.Aminocarbyne complexes[Fe_(2)Cp_(2)(CO)(L)(μ-CO)(μ-CNMe_(2))]^(+)(L=NH3,[2a]^(+);imidazole,[2b]^(+);pyrazole,[2c]^(+);thiourea,[2d]^(+);1,3,5-triaza-7-phosphadamantane,PTA,[2e]^(+))and thiocarbyne complexes[Fe_(2)Cp_(2)(CO)(L)(μ-CO)(μ-CSMe)]^(+)(L=imidazole,[4b]^(+);PTA,[4e]^(+);4-dimethylaminopyridine,DMAP,[4f]^(+);MeCN[4g]^(+)),five of which are unprecedented,were prepared,isolated as triflate salts and characterized by IR and NMR spectroscopy and X-ray diffraction in two cases.These nine diiron compounds were screened by cyclic voltammetry for their redox chemistry in acetonitrile and the electrocatalytic activity in the H_(2)evolution reaction from acetic acid.Two thiocarbyne complexes,featuring imidazole([4b]^(+))and DMAP([4f]^(+))as monodentate ligands emerged for their remarkable electrocatalytic activity,outperforming the previously-investigated cyanide derivatives.A mechanism for the electrocatalytic cycle is proposed based on combined electrochemical,spectroscopic and literature data.展开更多
基金the University of Pisa(Fondi di Ateneo 2020 and PRA_2020_39)for financial supportthe research project PNRR ECO-spoke 2-ECOSYSTER J33C22001240001.
文摘The development of efficient electrocatalysts for proton reduction(H_(2)production)based on earth-abundant metals is a scientific challenge with implications for energy storage and generation.Inspired by[FeFe]-hydrogenase enzymes,several compounds based on the{Fe_(2)Cp_(2)(CO)_(2)}framework have been investigated in this respect but,to date,only two charge-neutral derivatives,with a terminal cyanide and a bridging dimethylamino-(CNMe_(2)^(+))or methylthio-(CSMe^(+))carbyne ligand,were found to be effective electrocatalysts.Herein,we extended the investigation to related cationic derivatives with the cyanide ligand being replaced with various monodentate,hydrophilic N-P-or S-donor ligands.Aminocarbyne complexes[Fe_(2)Cp_(2)(CO)(L)(μ-CO)(μ-CNMe_(2))]^(+)(L=NH3,[2a]^(+);imidazole,[2b]^(+);pyrazole,[2c]^(+);thiourea,[2d]^(+);1,3,5-triaza-7-phosphadamantane,PTA,[2e]^(+))and thiocarbyne complexes[Fe_(2)Cp_(2)(CO)(L)(μ-CO)(μ-CSMe)]^(+)(L=imidazole,[4b]^(+);PTA,[4e]^(+);4-dimethylaminopyridine,DMAP,[4f]^(+);MeCN[4g]^(+)),five of which are unprecedented,were prepared,isolated as triflate salts and characterized by IR and NMR spectroscopy and X-ray diffraction in two cases.These nine diiron compounds were screened by cyclic voltammetry for their redox chemistry in acetonitrile and the electrocatalytic activity in the H_(2)evolution reaction from acetic acid.Two thiocarbyne complexes,featuring imidazole([4b]^(+))and DMAP([4f]^(+))as monodentate ligands emerged for their remarkable electrocatalytic activity,outperforming the previously-investigated cyanide derivatives.A mechanism for the electrocatalytic cycle is proposed based on combined electrochemical,spectroscopic and literature data.
