Mild Redox Complementation Enables H2 Activation by [FeFe]-Hydrogenase Models

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• 作者：James M. Camara ; Thomas B. Rauchfuss
• 刊名：Journal of the American Chemical Society
• 出版年：2011
• 出版时间：June 1, 2011
• 年：2011
• 卷：133
• 期：21
• 页码：8098-8101
• 全文大小：738K
• 年卷期：v.133,no.21(June 1, 2011)
• ISSN：1520-5126

文摘

Mild oxidants such as [Fe(C₅Me₅)₂]⁺ accelerate the activation of H₂ by [Fe₂[(SCH₂)₂NBn](CO)₃(dppv)(PMe₃)]⁺ ([1]⁺), despite the fact that the ferrocenium cation is incapable of oxidizing [1]⁺. The reaction is first-order in [1]⁺ and [H₂] but independent of the E_1/2 and concentration of the oxidant. The analogous reaction occurs with D₂ and proceeds with an inverse kinetic isotope effect of 0.75(8). The activation of H₂ is further enhanced with the tetracarbonyl [Fe₂[(SCH₂)₂NBn](CO)₄(dppn)]⁺ ([2]⁺), the first crystallographically characterized model for the H_ox state of the active site containing an amine cofactor. These studies point to rate-determining binding of H₂ followed by proton-coupled electron transfer. Relative to that by [1]⁺, the rate of H₂ activation by [2]⁺/Fc⁺ is enhanced by a factor of 10⁴ at 25 掳C.