Sulfur K-edge XAS and DFT calculations on [Fe4S 4]2+ clusters: Effects of H-bonding and structural distortion on covalency and spin topology

Abhishek Dey, Cara L. Roche, Marc A. Walters, Keith O. Hodgson, Britt Hedman, Edward I. Solomon

Research output: Contribution to journalArticle

Abstract

Sulfur K-edge X-ray absorption spectroscopy of a hydrogen-bonded elongated [Fe4S4]2+ cube is reported. The data show that this synthetic cube is less covalent than a normal compressed cube with no hydrogen bonding. DFT calculations reveal that the observed difference in electronic structure has significant contributions from both the cluster distortion and from hydrogen bonding. The elongated and compressed Fe 4S4 structures are found to have different spin topologies (i.e., orientation of the delocalized Fe2S2 subclusters which are antiferromagnetically coupled to each other). It is suggested that the H-bonding interaction with the counterion does not contribute to the cluster elongation. A magneto-structural correlation is developed for the Fe 4S4 cube that is used to identify the redoxactive Fe 2S2 subclusters in active sites of HiPIP and ferredoxin proteins involving these clusters.

Original languageEnglish (US)
Pages (from-to)8349-8354
Number of pages6
JournalInorganic Chemistry
Volume44
Issue number23
DOIs
StatePublished - Nov 14 2005

ASJC Scopus subject areas

  • Physical and Theoretical Chemistry
  • Inorganic Chemistry

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