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Published December 26, 2013 | Supplemental Material + Accepted Version
Journal Article Open

Heterometallic Triiron-Oxo/Hydroxo Clusters: Effect of Redox-Inactive Metals

Abstract

A series of tetranuclear oxo/hydroxo clusters comprised of three Fe centers and a redox-inactive metal (M) of various charge is reported. Crystallographic studies show an unprecedented Fe_3M(μ_4-O)(μ_2-OH) core that remains intact upon changing M or the oxidation state of iron. Electrochemical studies reveal that the reduction potentials (E_(1/2)) span a window of 500 mV and depend upon the Lewis acidity of M. Using the pK_a of the M-aqua complex as a measure of Lewis acidity, these compounds display a linear dependence between E1/2 and acidity, with a slope of ∼70 mV per pK_a unit. The current study of [Fe_3MO(OH)] and previous ones of [Mn_3MO_n] (n = 2,4) moieties support the generality of the above relationship between the reduction potentials of heterometallic oxido clusters and the Lewis acidity of incorporated cations, as applied to clusters of different redox-active metals.

Additional Information

© 2013 American Chemical Society. Published In Issue December 26, 2013; Article ASAP December 16, 2013; Just Accepted Manuscript December 04, 2013; Received: October 13, 2013. The authors declare no competing financial interest. This work was supported by the California Institute of Technology, the Searle Scholars Program, the NSF CAREER CHE-1151918 (T.A.), a Camille & Henry Dreyfus Environmental Chemistry Fellowship (D.E.H.), and a Resnick Sustainability Institute graduate fellowship (D.L.). T.A. is a Sloan and Cottrell Fellow. We thank Larry M. Henling and Dr. Michael Takase for assistance with crystallography and Prof. Jonas C. Peters for use of a Mössbauer spectrometer. Collection of Mössbauer data was made possible by use of an instrument purchased with funds from the National Science Foundation Center for Chemical Innovation on Solar Fuels (CCI Solar, Grant CHE-1305124). The Bruker KAPPA APEXII X-ray diffractometer was purchased via an NSF Chemistry Research Instrumentation award to Caltech (CHE-0639094). We acknowledge the Gordon and Betty Moore Foundation, the Beckman Institute, and the Sanofi-Aventis BRP at Caltech for their generous support of the Molecular Observatory at Caltech. Operations at SSRL are supported by the U.S. DOE and NIH.

Attached Files

Accepted Version - nihms550402.pdf

Supplemental Material - ja4104974_si_001.pdf

Supplemental Material - ja4104974_si_002.zip

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Additional details

Created:
August 19, 2023
Modified:
October 25, 2023