Models for the active site in [FeFe] hydrogenase with iron-bound ligands derived from bis-, tris-, and tetrakis(mercaptomethyl)silanes.
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)].
Apfel
Ulf-Peter
UP
Institut für Anorganische und Analytische Chemie, Friedrich-Schiller-Universität Jena, August-Bebel-Strasse 2, D-07743 Jena, Germany.
Troegel
Dennis
D
Halpin
Yvonne
Y
Tschierlei
Stefanie
S
Uhlemann
Ute
U
Görls
Helmar
H
Schmitt
Michael
M
Popp
Jürgen
J
Dunne
Peter
P
Venkatesan
Munuswamy
M
Coey
Michael
M
Rudolph
Manfred
M
Vos
Johannes G
JG
Tacke
Reinhold
R
Weigand
Wolfgang
W
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
D007506:Iron-Sulfur Proteins; D008024:Ligands; D009942:Organometallic Compounds; D012821:Silanes; D002248:Carbon Monoxide; D007501:Iron; C118830:iron hydrogenase; D006864:Hydrogenase; D012825:Silicon