Modeling the Active Site of [NiFe] Hydrogenases and the [NiFeu] Subsite of the C-Cluster of Carbon Monoxide Dehydrogenases: Low-Spin Iron(II) Versus High-Spin Iron(II)

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• 作者：Katharina Weber ; 脰zlen F. Erdem ; Eckhard Bill ; Thomas Weyherm眉ller ; Wolfgang Lubitz
• 刊名：Inorganic Chemistry
• 出版年：2014
• 出版时间：June 16, 2014
• 年：2014
• 卷：53
• 期：12
• 页码：6329-6337
• 全文大小：390K
• 年卷期：v.53,no.12(June 16, 2014)
• ISSN：1520-510X

文摘

A series of four [S₂Ni(渭-S)₂FeCp*Cl] compounds with different tetradentate thiolate/thioether ligands bound to the Ni(II) ion is reported (Cp* = C₅Me₅). The {S₂Ni(渭-S)₂Fe} core of these compounds resembles structural features of the active site of [NiFe] hydrogenases. Detailed analyses of the electronic structures of these compounds by M枚ssbauer and electron paramagnetic resonance spectroscopy, magnetic measurements, and density functional theory calculations reveal the oxidation states Ni(II) low spin and Fe(II) high spin for the metal ions. The same electronic configurations have been suggested for the C_red1 state of the C-cluster [NiFe_u] subsite in carbon monoxide dehydrogenases (CODH). The Ni鈥揊e distance of 3 脜 excludes a metal鈥搈etal bond between nickel and iron, which is in agreement with the computational results. Electrochemical experiments show that iron is the redox active site in these complexes, performing a reversible one-electron oxidation. The four complexes are discussed with regard to their similarities and differences both to the [NiFe] hydrogenases and the C-cluster of Ni-containing CODH.