Models for the Active Site in [FeFe] Hydrogenase with Iron-Bound Ligands Derived from Bis-, Tris-, and Tetrakis(mercaptomethyl)silanes

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• 作者：Ulf-Peter Apfel ; Dennis Troegel ; Yvonne Halpin ; Stefanie Tschierlei ; Ute Uhlemann ; Helmar Grls ; Michael Schmitt ; Jrgen Popp ; Peter Dunne ; Munuswamy Venkatesan ; Michael Coey ; Manfred Rudolph ; Johannes
• 刊名：Inorganic Chemistry
• 出版年：2010
• 出版时间：November 1, 2010
• 年：2010
• 卷：49
• 期：21
• 页码：10117-10132
• 全文大小：1345K
• 年卷期：v.49,no.21(November 1, 2010)
• ISSN：1520-510X

文摘

A series of multifunctional (mercaptomethyl)silanes of the general formula type R_nSi(CH₂SH)_4−n (n = 0−2; R = organyl) was synthesized, starting from the corresponding (chloromethyl)silanes. They were used as multidentate ligands for the conversion of dodecacarbonyltriiron, Fe₃(CO)₁₂, into iron carbonyl complexes in which the deprotonated (mercaptomethyl)silanes act as μ-bridging ligands. These complexes can be regarded as models for the [FeFe] hydrogenase. They were characterized by elemental analyses (C, H, S), NMR spectroscopic studies (¹H, ¹³C, ²⁹Si), and single-crystal X-ray diffraction. Their electrochemical properties were investigated by cyclic voltammetry to disclose a new mechanism for the formation of dihydrogen catalyzed by these compounds, whereby one sulfur atom was protonated in the catalytic cycle. The reaction of the tridentate ligand MeSi(CH₂SH)₃ with Fe₃(CO)₁₂ yielded a tetranuclear cluster compound. A detailed investigation by X-ray diffraction, electrochemical, Raman, Mssbauer, and susceptibility techniques indicates that for this compound initially [Fe₂{μ-MeSi(CH₂S)₂CH₂SH}(CO)₆] is formed. This dinuclear complex, however, is slowly transformed into the tetranuclear species [Fe₄{μ-MeSi(CH₂S)₃}₂(CO)₈].