The Complete Characterization of a Reduced Biomimetic [2 Fe-2 S] Cluster


  • Financial support by the DFG (International Research Training Group GRK 1422 “Metal Sites in Biomolecules: Structures, Regulation and Mechanisms”; see and the Cusanuswerk (PhD fellowship for A.A.) is gratefully acknowledged.


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Cores and effect: A biomimetic [2 Fe-2 S] cluster is characterized crystallographically in both the [FeIIIFeIII] and the mixed-valent [FeIIIFeII] forms—the [2 Fe-2 S] cores show only minor geometric differences. The reduced form has an S=1/2 ground state and the unpaired electron is partially delocalized over the cluster core. The experimental effective coupling constant predicts the position of the intervalence charge transfer band in the IR regime.