[FeFe]-Hydrogenase H-Cluster Mimics with Unique Planar μ-(SCH 2 ) 2 ER 2 Linkers (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 GeR2 and SnR2 groups 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)6 cluster and low torsional strain for GeMe2 and SnMe2 moieties 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)6 cores bridged by CH2SnR2CH2, R=Me, Ph, linkers were also obtained and characterized.
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Chemistry - A European Journal, Wiley-VCH Verlag, 2017, 23 (2), pp.346 - 359. 〈10.1002/chem.201603843〉
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http://hal.univ-brest.fr/hal-01624527
Contributeur : Nicolas Renard <>
Soumis le : jeudi 26 octobre 2017 - 13:32:12
Dernière modification le : mercredi 11 avril 2018 - 10:56:01

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Hassan Abul-Futouh, Laith R. Almazahreh, Takahiro Sakamoto, Nhu Y. T. Stessman, Dennis L. Lichtenberger, et al.. [FeFe]-Hydrogenase H-Cluster Mimics with Unique Planar μ-(SCH 2 ) 2 ER 2 Linkers (E=Ge and Sn). Chemistry - A European Journal, Wiley-VCH Verlag, 2017, 23 (2), pp.346 - 359. 〈10.1002/chem.201603843〉. 〈hal-01624527〉

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