Activation of proton by the two-electron reduction of a di-iron organometallic complex

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• 作者：Jean-Franç ; ois Capon ; Fré ; dé ; ric Gloaguen ; Philippe Schollhammer and Jean Talarmin
• 关键词：Homogeneous catalysis ; Hydrogenase model ; Iron ; Proton reduction ; Voltammetry simulation
• 刊名：Journal of Electroanalytical Chemistry
• 出版年：2006
• 期刊代码：27_00220728
• 类别：ph
• 出版时间：15 September 2006
• 卷：595
• 期：1
• 页码：47-52
• 文件大小：223 K

摘要

Fe₂(bdt)(CO)₆ (1) (bdt = benzenedithiolate) exhibits a chemically reversible two-electron reduction at −1.27 V vs. Fc^+/0 in CH₃CN + Bu₄NPF₆ electrolyte. The increase in height of the reduction wave of complex 1 upon increasing the concentration of toluenesulfonic acid (pK_a 8 in CH₃CN) is consistent with a catalysis of the proton reduction reaction (k_cat 500 M⁻¹ s⁻¹). The reaction scheme, derived from the simulation of the voltammetric responses, involves the initial formation of the dianion 1²⁻ followed by two successive reactions with acid. The last protonation step is the rate determining step in the catalytic cycle. Using experiments conducted with acetic acid (pK_a 23 in CH₃CN), we further shown that the intermediate species 1H⁻ is a significantly weaker base than the dianion 1²⁻.