title: Effect of the S-to-S bridge on the redox properties and H2activation performance of diiron complexes related to the [FeFe]-hydrogenase active site.
abstract: Three biomimetic models of the [FeFe]-hydrogenase active site, namely diiron dithiolates of [(μ-edt){Fe(CO)3}{Fe(CO)(κ2-PNP)}] (1, edt = ethane-1,2-dithiolate, PNP = Ph2PCH2N(nPr)CH2PPh2), [(μ-bdtMe){Fe(CO)3}{Fe(CO)(κ2-PNP)}] (2, bdtMe = 4-methylbenzene-1,2-dithiolate), and [(μ-adtBn){Fe(CO)3}{Fe(CO)(κ2-PNP)}] (3, adtBn = N-benzyl-2-azapropane-1,3-dithiolate), were prepared and structurally characterized. These complexes feature the same PNP ligand but different S-to-S bridges. Influence of the S-to-S bridge on the electrochemical properties and chemical oxidation reactivity of 1-3 was studied by cyclic voltammetry and by in situ IR spectroscopy. The results reveal that the S-to-S bridge has a considerable effect on the oxidation reactivity of 1-3 and on the stability of in situ generated single-electron oxidized complexes, [1]+, [2]+, and [3]+. The performances of [1]+and [2]+for H2activation were explored in the presence of a mild chemical oxidant, while rapid decomposition of [3]+thwarted the further study of this complex. Gratifyingly, 1 was found to be catalytically active, although in a low turnover number, for H2oxidation in the presence of excess mild oxidant and a proton trapper under 1 atm H2at room temperature.
authors.affiliation: State Key Laboratory of Fine Chemicals, DUT-KTH Joint Education and Research Center on Molecular Devices, Dalian University of Technology, Dalian 116024, China. symbueno@dlut.edu.cn.
authors.forename: Minglun
authors.initials: M
authors.lastname: Cheng
authors.forename: Mei
authors.initials: M
authors.lastname: Wang
authors.forename: Dehua
authors.initials: D
authors.lastname: Zheng
authors.forename: Licheng
authors.initials: L
authors.lastname: Sun
mesh_terms: D040761:Biomimetic Materials / Q000737:chemistry*; D002384:Catalysis; D020134:Catalytic Domain; D018360:Crystallography, X-Ray; D005290:Ferric Compounds / Q000737:chemistry*; D006859:Hydrogen / Q000737:chemistry*; D006864:Hydrogenase / Q000737:chemistry*; D008024:Ligands; D008958:Models, Molecular; D010084:Oxidation-Reduction; D010720:Phosphines / Q000737:chemistry; D011522:Protons; D013438:Sulfhydryl Compounds / Q000737:chemistry*
chemical_list: D005290:Ferric Compounds; D008024:Ligands; D010720:Phosphines; D011522:Protons; D013438:Sulfhydryl Compounds; C002007:dithiol-iron(III)-sulfide complex; D006859:Hydrogen; D006864:Hydrogenase