Triptycene-Based, Carboxylate-Bridged Biomimetic Diiron(II) Complexes
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Lippard_Triptycene-based.pdf
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Author(s)
Li, Yang
Soe, Chan Myae Myae
Wilson, Justin J.
Apfel, Ulf-Peter
Lippard, Stephen J.
Tuang, Suan L.
Date Issued
February 2013
Journal
European Journal of Inorganic Chemistry
Publisher
Wiley Blackwell
Citation
Li, Yang, Chan Myae Myae Soe, Justin J. Wilson, Suan Lian Tuang, Ulf-Peter Apfel, and Stephen J. Lippard. “Triptycene-Based, Carboxylate-Bridged Biomimetic Diiron(II) Complexes.” European Journal of Inorganic Chemistry 2013, no. 12 (February 7, 2013): 2011–2019.
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Author's final manuscript
Abstract
A triptycene-based bis(benzimidazole) ester ligand, L3, was designed to enhance the electron-donating ability of the heterocyclic nitrogen atoms relative to those of the first-generation bis(benzoxazole) analogs, L1 and L2. A convergent synthesis of L3 was designed and executed. Three-component titration experiments using UV/Vis spectroscopy revealed that the desired diiron(II) complex could be obtained with a 1:2:1 ratio of L3/Fe(OTf)[subscript 2](MeCN)[subscript 2]/external carboxylate reactants. X-ray crystallographic studies of two diiron complexes derived in this manner from L3 revealed their formulas to be [Fe[subscript 2]L3(μ-OH)(μ-O[subscript 2]CR)(OTf)2], where R = 2,6-bis(p-tolyl)phenyl (7) or triphenylmethyl (8). The structures are similar to that of a diiron complex derived from L1, [Fe[subscript 2]L1(μ-OH)(μ-O[subscript 2]CAr[superscript Tol])(OTf)[subscript 2]] (9), a notable difference being that, in 7 and 8, the geometry at iron more closely resembles square-pyramidal than trigonal-bipyramidal. Mössbauer spectroscopic analyses of 7 and 8 indicate the presence of high-spin diiron(II) cores. These results demonstrate the importance of substituting benzimidazole for benzoxazole for assembling biomimetic diiron complexes with syn disposition of two N-donor ligands, as found in O[subscript 2]-activating carboxylate-bridged diiron centers in biological systems.
MIT Department
Harvard University--MIT Division of Health Sciences and Technology
Massachusetts Institute of Technology. Department of Chemistry
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DOI of Published Version
https://doi.org/10.1002/ejic.201201387
