title: [FeFe]-Hydrogenase H-Cluster Mimics with Unique Planar μ-(SCH2)2ER2Linkers (E=Ge and Sn).
abstract: Analogues of the [2Fe-2S] subcluster of hydrogenase enzymes in which the central group of the three-atom chain linker between the sulfur atoms is replaced by GeR2and SnR2groups are studied. The six-membered FeSCECS rings in these complexes (E=Ge or Sn) adopt an unusual conformation with nearly co-planar SCECS atoms perpendicular to the Fe-Fe core. Computational modelling traces this result to the steric interaction of the Me groups with the axial carbonyls of the Fe2(CO)6cluster and low torsional strain for GeMe2and SnMe2moieties owing to the long C-Ge and C-Sn bonds. Gas-phase photoelectron spectroscopy of these complexes shows a shift of ionization potentials to lower energies with substantial sulfur orbital character and, as supported by the computations, an increase in sulfur character in the predominantly metal-metal bonding HOMO. Cyclic voltammetry reveals that the complexes follow an ECE-type reduction mechanism (E=electron transfer and C=chemical process) in the absence of acid and catalysis of proton reduction in the presence of acid. Two cyclic tetranuclear complexes featuring the sulfur atoms of two Fe2S2(CO)6cores bridged by CH2SnR2CH2, R=Me, Ph, linkers were also obtained and characterized.
authors.affiliation: Institut für Anorganische und Analytische Chemie, Friedrich-Schiller-Universität Jena, Humboldt Str. 8, 07743, Jena, Germany.
authors.forename: Hassan
authors.initials: H
authors.lastname: Abul-Futouh
authors.affiliation: Institut für Anorganische und Analytische Chemie, Friedrich-Schiller-Universität Jena, Humboldt Str. 8, 07743, Jena, Germany.
authors.forename: Laith R
authors.initials: LR
authors.lastname: Almazahreh
authors.affiliation: Department of Chemistry and Biochemistry, The University of Arizona, Tucson, AZ, 85721, USA.
authors.forename: Takahiro
authors.initials: T
authors.lastname: Sakamoto
authors.affiliation: Department of Chemistry and Biochemistry, The University of Arizona, Tucson, AZ, 85721, USA.
authors.forename: Nhu Y T
authors.initials: NY
authors.lastname: Stessman
authors.affiliation: Department of Chemistry and Biochemistry, The University of Arizona, Tucson, AZ, 85721, USA.
authors.forename: Dennis L
authors.initials: DL
authors.lastname: Lichtenberger
authors.affiliation: Department of Chemistry and Biochemistry, The University of Arizona, Tucson, AZ, 85721, USA.
authors.forename: Richard S
authors.initials: RS
authors.lastname: Glass
authors.affiliation: Institut für Anorganische und Analytische Chemie, Friedrich-Schiller-Universität Jena, Humboldt Str. 8, 07743, Jena, Germany.
authors.forename: Helmar
authors.initials: H
authors.lastname: Görls
authors.affiliation: Chemistry Department, Jordan University of Science and Technology, Irbid, 22110, Jordan.
authors.forename: Mohammad
authors.initials: M
authors.lastname: El-Khateeb
authors.affiliation: UMR CNRS 6521, Université de Bretagne Occidentale, 6 avenue Le Gorgeu, C.S. 93837, 29238, Brest-Cedex, France.
authors.forename: Philippe
authors.initials: P
authors.lastname: Schollhammer
authors.affiliation: Section of Heteroorganic Compounds, University of Lodz, Tamka 12, 91-403, Łódź, Poland.
authors.forename: Grzegorz
authors.initials: G
authors.lastname: Mloston
authors.affiliation: Institut für Anorganische und Analytische Chemie, Friedrich-Schiller-Universität Jena, Humboldt Str. 8, 07743, Jena, Germany.
authors.forename: Wolfgang
authors.initials: W
authors.lastname: Weigand
mesh_terms: D040761:Biomimetic Materials / Q000737:chemistry*; D002384:Catalysis; D020134:Catalytic Domain; D056831:Coordination Complexes / Q000737:chemistry*; D018360:Crystallography, X-Ray; D005857:Germanium / Q000737:chemistry*; D006864:Hydrogenase / Q000737:chemistry*; D058085:Iron Compounds / Q000737:chemistry*; D007506:Iron-Sulfur Proteins / Q000737:chemistry; D008024:Ligands; D008958:Models, Molecular; D008968:Molecular Conformation; D017971:Tin Compounds / Q000737:chemistry*
chemical_list: D056831:Coordination Complexes; D058085:Iron Compounds; D007506:Iron-Sulfur Proteins; D008024:Ligands; D017971:Tin Compounds; D005857:Germanium; D006864:Hydrogenase
keywords: conformational analysis; density functional calculations; electrocatalysis; photoelectron; sulfur