title: Models for the active site in [FeFe] hydrogenase with iron-bound ligands derived from bis-, tris-, and tetrakis(mercaptomethyl)silanes.
abstract: A series of multifunctional (mercaptomethyl)silanes of the general formula type R(n)Si(CH(2)SH)(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, Fe(3)(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 ((1)H, (13)C, (29)Si), 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(CH(2)SH)(3) with Fe(3)(CO)(12) yielded a tetranuclear cluster compound. A detailed investigation by X-ray diffraction, electrochemical, Raman, Mössbauer, and susceptibility techniques indicates that for this compound initially [Fe(2){μ-MeSi(CH(2)S)(2)CH(2)SH}(CO)(6)] is formed. This dinuclear complex, however, is slowly transformed into the tetranuclear species [Fe(4){μ-MeSi(CH(2)S)(3)}(2)(CO)(8)].
authors.affiliation: Institut für Anorganische und Analytische Chemie, Friedrich-Schiller-Universität Jena, August-Bebel-Strasse 2, D-07743 Jena, Germany.
authors.forename: Ulf-Peter
authors.initials: UP
authors.lastname: Apfel
authors.forename: Dennis
authors.initials: D
authors.lastname: Troegel
authors.forename: Yvonne
authors.initials: Y
authors.lastname: Halpin
authors.forename: Stefanie
authors.initials: S
authors.lastname: Tschierlei
authors.forename: Ute
authors.initials: U
authors.lastname: Uhlemann
authors.forename: Helmar
authors.initials: H
authors.lastname: Görls
authors.forename: Michael
authors.initials: M
authors.lastname: Schmitt
authors.forename: Jürgen
authors.initials: J
authors.lastname: Popp
authors.forename: Peter
authors.initials: P
authors.lastname: Dunne
authors.forename: Munuswamy
authors.initials: M
authors.lastname: Venkatesan
authors.forename: Michael
authors.initials: M
authors.lastname: Coey
authors.forename: Manfred
authors.initials: M
authors.lastname: Rudolph
authors.forename: Johannes G
authors.initials: JG
authors.lastname: Vos
authors.forename: Reinhold
authors.initials: R
authors.lastname: Tacke
authors.forename: Wolfgang
authors.initials: W
authors.lastname: Weigand
mesh_terms: D055162:Biocatalysis; D002248:Carbon Monoxide / Q000737:chemistry; D020134:Catalytic Domain; D004563:Electrochemistry; D006864:Hydrogenase / Q000737:chemistry / Q000378:metabolism*; D007501:Iron / Q000737:chemistry*; D007506:Iron-Sulfur Proteins / Q000737:chemistry / Q000378:metabolism*; D008024:Ligands; D008958:Models, Molecular; D015394:Molecular Structure; D009942:Organometallic Compounds / Q000138:chemical synthesis / Q000737:chemistry*; D012821:Silanes / Q000138:chemical synthesis / Q000737:chemistry*; D012825:Silicon
chemical_list: D007506:Iron-Sulfur Proteins; D008024:Ligands; D009942:Organometallic Compounds; D012821:Silanes; D002248:Carbon Monoxide; D007501:Iron; C118830:iron hydrogenase; D006864:Hydrogenase; D012825:Silicon