Book of Abstracts - Ruhr-Universität Bochum

OP-23
ISBOMC `10 5.7 – 9.7. 2010 Ruhr-Universität Bochum
Models for the Active Site in [FeFe] Hydrogenase with Silicon-containing Ligands
Ulf-Peter Apfel, a Dennis Troegel, b Yvonne Halpin, c Stefanie Tschierlei, d Ute Uhlemann, d Helmar Görls, a
Michael Schmitt, d Jürgen Popp, d P. Dunne, e M. Venkatesan, e Michael Coey, e,* Manfred Rudolph, a,*
Johannes G. Vos, c,* Reinhold Tacke, b,* Wolfgang Weigand a,*
a Institut für Anorganische und Analytische Chemie, Friedrich-Schiller-Universität Jena, August-Bebel-
Straße 2, D-07743 Jena, Germany,wolfgang.weigand@uni-jena.de. b Institut für Anorganische Chemie,
Universität Würzburg, Am Hubland, D-97074 Würzburg, Germany. c Solar Energy Conversion SRC,
School of Chemical Sciences, Dublin City University, Dublin 9, Ireland. d Institut für Physikalische
Chemie, Friedrich-Schiller-Universität Jena, Helmholtzweg 4, D-07743 Jena, Germany. e SFI-Trinity
Nanoscience Laboratory, Physics Department, Trinity College, Dublin 2, Ireland.
A series of multifunctional (mercaptomethyl)silanes of the general formula type RnSi(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 m-bridging ligands. These complexes can be
regarded as models for the [FeFe] hydrogenase. They were characterized by elemental analyses (C, H, S),
NMR 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(CH2SH)3 with Fe3(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 a [Fe2{MeSi(CH2S)2CH2SH}(CO)6] is formed. This
dinuclear complex is however slowly transformed into the tetranuclear species
[Fe4{MeSi(CH2S)3}2(CO)8].
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