Hydrogen Production Catalyzed by Bidirectional, Biomimetic Models of the [FeFe]-Hydrogenase Active Site

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• 作者：James C. Lansing ; James M. Camara ; Danielle E. Gray ; Thomas B. Rauchfuss
• 刊名：Organometallics
• 出版年：2014
• 出版时间：October 27, 2014
• 年：2014
• 卷：33
• 期：20
• 页码：5897-5906
• 全文大小：523K
• ISSN：1520-6041

文摘

Active site mimics of [FeFe]-hydrogenase are shown to be bidirectional catalysts, producing H₂ upon treatment with protons and reducing equivalents. This reactivity complements the previously reported oxidation of H₂ by these same catalysts in the presence of oxidants. The complex Fe₂(adt^Bn)(CO)₃(dppv)(PFc*^Et₂) ([1]⁰; adt^Bn = (SCH₂)₂NBn, dppv = cis-1,2-bis(diphenylphosphino)ethylene, PFc*^Et₂ = Et₂PCH₂C₅Me₄FeCp*) reacts with excess [H(OEt₂)₂]BAr^F₄ (BAr^F₄^{鈥?/sup> = B(C₆H₃-3,5-(CF₃)₂)₄鈥?/sup>) to give 鈭?.5 equiv of H₂ and [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 FeIFeI core. 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 catalytically inactive 渭-hydride derivative [渭-H3]+. Replacement of the adt in [1]0 with 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.}