Synthesis of diiron hydrogenase mimics bearing hydroquinone and related ligands. Electrochemical and computational studies of the mechanism of hydrogen production and the role of O-H⋯S hydrogen bonding

Jinzhu Chen, Aaron K. Vannucci, Charles A. Mebi, Noriko Okumura, Susan C. Borowski, Matthew Swenson, L. Tori Lockett, Dennis H. Evans, Richard S. Glass, Dennis L. Lichtenberger

Research output: Contribution to journalArticle

55 Scopus citations

Abstract

A new synthetic method for annulating hydroquinones to Fe2S 2(CO)6 moieties is reported. Piperidine catalyzed a multistep reaction between Fe2(μ-SH)2(CO)6 and quinones to afford bridged adducts in 26-76% yields. The hydroquinone adducts undergo reversible two-electron reductions. In the presence of acetic acid, hydrogen is produced catalytically with these adducts at potentials more negative than that of the initial reversible reduction. Spectroscopic studies suggest the presence of intramolecular hydrogen bonding between the phenolic OH groups and the adjacent sulfur atoms. Computations, which are in good agreement with the electrochemical studies and spectroscopic data, indicate that the hydrogen bonding is most important in the reduced forms of the catalysts. This hydrogen bonding lowers the reduction potential for catalysis but also lowers the basicity and thereby the reactivity of the catalysts.

Original languageEnglish (US)
Pages (from-to)5330-5340
Number of pages11
JournalOrganometallics
Volume29
Issue number21
DOIs
StatePublished - Nov 8 2010

ASJC Scopus subject areas

  • Physical and Theoretical Chemistry
  • Organic Chemistry
  • Inorganic Chemistry

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