Synthesis and characterization of diiron diselenolato complexes including Iron Hydrogenase models

Mohammad K. Harb, Tobias Niksch, Jochen Windhager, Helmar Görls, Rudolf Holze, L. Tori Lockett, Noriko Okumura, Dennis H. Evans, Richard S. Glass, Dennis L. Lichtenberger, Mohammad El-khateeb, Wolfgang Weigand

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73 Scopus citations

Abstract

Diiron diselenolato complexes have been prepared as models of the active site of [FeFe]-hydrogenases. Treatment of Fe 3(CO) 12 with 1 equiv of 1,3-diselenocyanatopropane (1) in THF at reflux afforded the model compound Fe 2(μ-Se 2C 3H 6)(CO) 6 (2) in 68% yield. The analogous methyl-substituted complex, Fe 2(μ-Se 2C 3H 5CH3)(CO) 6 (3), was obtained from the reaction of Fe 3(CO) 12 with the in situ generated compound 3-methyl-1,2-diselenolane (4). In contrast, the reaction of Fe 3(CO) 12 with 1,3,5-triselenacy-clohexane (5) produced a mixture of Fe 22,k-Se,C-SeCH 2SeCH 2)(CO) 6 (6), Fe 2[(μ- SeCH 2) 2Se](CO) 6 (7), and Fe 2(μ- Se 2CH 2)(CO) 6 (8). Compounds 2, 3, 6, and 7 were characterized by IR, 1H, 13C, and 77Se NMR spectroscopy, mass spectrometry, elemental analysis, and X-ray single-crystal structure analysis. The He I and He II photoelectron spectra for 3 are reported, and the electronic structure is further analyzed with the aid of DFT computations. The calculated reorganization energy of the cation of 3 to the "rotated" structure, which has a semibridging carbonyl ligand, is less than that of the analogous complexes with sulfur instead of selenium. Complexes 2 and 3 have been proved to be catalysts for electrochemical reduction of protons from the weak acids pivalic and acetic acid, respectively, to give hydrogen.

Original languageEnglish (US)
Pages (from-to)1039-1048
Number of pages10
JournalOrganometallics
Volume28
Issue number4
DOIs
StatePublished - Feb 23 2009

ASJC Scopus subject areas

  • Physical and Theoretical Chemistry
  • Organic Chemistry
  • Inorganic Chemistry

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