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Published November 6, 2017 | Supplemental Material + Accepted Version
Journal Article Open

Tetranuclear Fe Clusters with a Varied Interstitial Ligand: Effects on the Structure, Redox Properties, and Nitric Oxide Activation

Abstract

A new series of tetranuclear Fe clusters displaying an interstitial μ_4-F ligand was prepared for a comparison to previously reported μ_4-O analogues. With a single nitric oxide (NO) coordinated as a reporter of small-molecule activation, the μ_4-F clusters were characterized in five redox states, from Fe^(II)_3{FeNO}^8 to Fe^(III)_3{FeNO}^7, with NO stretching frequencies ranging from 1680 to 1855 cm^(–1), respectively. Despite accessing more reduced states with an F– bridge, a two-electron reduction of the distal Fe centers is necessary for the μ_4-F clusters to activate NO to the same degree as the μ_4-O system; consequently, NO reactivity is observed at more positive potentials with μ_4-O than μ_4-F. Moreover, the μ_4-O ligand better translates redox changes of remote metal centers to diatomic ligand activation. The implication for biological active sites is that the higher-charge bridging ligand is more effective in tuning cluster properties, including the involvement of remote metal centers, for small-molecule activation.

Additional Information

© 2017 American Chemical Society. Received: August 17, 2017. Publication Date (Web): October 20, 2017. This research was supported by the NIH (Grant R01-GM102687B) and the Dreyfus Teacher–Scholar Program (to T.A.). C.J.R. thanks the Resnick Sustainability Institute at Caltech for a fellowship. We thank Mike Takase and Larry Henling for assistance with crystallography and Jonas Peters for use of his laboratory's Mössbauer spectrometer. C.J.R. is grateful to Graham de Ruiter and Niklas Thompson for insightful discussions. The authors declare no competing financial interest.

Attached Files

Accepted Version - nihms915080.pdf

Supplemental Material - ic7b02114_si_001.pdf

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