title: Hydrogen Production Catalyzed by Bidirectional, Biomimetic Models of the [FeFe]-Hydrogenase Active Site.
abstract: Active site mimics of [FeFe]-hydrogenase are shown to be bidirectional catalysts, producing H2upon treatment with protons and reducing equivalents. This reactivity complements the previously reported oxidation of H2by these same catalysts in the presence of oxidants. The complex Fe2(adtBn)(CO)3(dppv)(PFc*Et2) ([1]0; adtBn= (SCH2)2NBn, dppv =cis-1,2-bis(diphenylphosphino)ethylene, PFc*Et2= Et2PCH2C5Me4FeCp*) reacts with excess [H(OEt2)2]BArF4(BArF4-= B(C6H3-3,5-(CF3)2)4-) to give ∼0.5 equiv of H2and [Fe2(adtBnH)(CO)3(dppv)(PFc*Et2)]2+([1H]2+). The species [1H]2+consists of a ferrocenium ligand, an N-protonated amine, and an FeIFeIcore. In the presence of additional reducing equivalents in the form of decamethylferrocene (Fc*), hydrogen evolution is catalytic, albeit slow. The related catalyst Fe2(adtBn)(CO)3(dppv)(PMe3) (3) behaves similarly in the presence of Fc*, except that in the absence of excess reducing agent it converts to the catalyticallyinactive μ-hydride derivative [μ-H3]+. Replacement of the adt in [1]0with propanedithiolate (pdt) results in a catalytically inactive complex. In the course of synthesizing [FeFe]-hydrogenase mimics, new routes to ferrocenylphosphine ligands and nonamethylferrocene were developed.
authors.affiliation: Department of Chemistry, University of Illinois 600 S. Goodwin Avenue Urbana, Illinois 61801, United States.
authors.forename: James C
authors.initials: JC
authors.lastname: Lansing
authors.affiliation: Department of Chemistry, University of Illinois 600 S. Goodwin Avenue Urbana, Illinois 61801, United States.
authors.forename: James M
authors.initials: JM
authors.lastname: Camara
authors.affiliation: Department of Chemistry, University of Illinois 600 S. Goodwin Avenue Urbana, Illinois 61801, United States.
authors.forename: Danielle E
authors.initials: DE
authors.lastname: Gray
authors.affiliation: Department of Chemistry, University of Illinois 600 S. Goodwin Avenue Urbana, Illinois 61801, United States.
authors.forename: Thomas B
authors.initials: TB
authors.lastname: Rauchfuss