Crystallographic Evidence for a Sterically Induced Ferryl Tilt in a Non-Heme Oxoiron(IV) Complex that Makes it a Better Oxidant

Waqas Rasheed, Apparao Draksharapu, Saikat Banerjee, Victor G Young, Ruixi Fan, Yisong Guo, M. Ozerov, Joscha Nehrkorn, J. Krzystek, Joshua Telser, Larry Que

Research output: Contribution to journalArticle

9 Citations (Scopus)

Abstract

Oxoiron(IV) units are often implicated as intermediates in the catalytic cycles of non-heme iron oxygenases and oxidases. The most reactive synthetic analogues of these intermediates are supported by tetradentate tripodal ligands with N-methylbenzimidazole or quinoline donors, but their instability precludes structural characterization. Herein we report crystal structures of two [FeIV(O)(L)]2+ complexes supported by pentadentate ligands incorporating these heterocycles, which show longer average Fe–N distances than the complex with only pyridine donors. These longer distances correlate linearly with log k2′ values for O- and H-atom transfer rates, suggesting that weakening the ligand field increases the electrophilicity of the Fe=O center. The sterically bulkier quinoline donors are also found to tilt the Fe=O unit away from a linear N-Fe=O arrangement by 10°.

Original languageEnglish (US)
Pages (from-to)9387-9391
Number of pages5
JournalAngewandte Chemie - International Edition
Volume57
Issue number30
DOIs
StatePublished - Jul 20 2018

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Oxidants
Ligands
Oxygenases
Pyridine
Oxidoreductases
Iron
Crystal structure
Atoms
quinoline

Keywords

  • hydrogen atom transfer (HAT)
  • non-heme iron complexes
  • oxoiron(IV) complexes
  • two-state reactivity

PubMed: MeSH publication types

  • Journal Article
  • Research Support, U.S. Gov't, Non-P.H.S.
  • Research Support, Non-U.S. Gov't

Cite this

Crystallographic Evidence for a Sterically Induced Ferryl Tilt in a Non-Heme Oxoiron(IV) Complex that Makes it a Better Oxidant. / Rasheed, Waqas; Draksharapu, Apparao; Banerjee, Saikat; Young, Victor G; Fan, Ruixi; Guo, Yisong; Ozerov, M.; Nehrkorn, Joscha; Krzystek, J.; Telser, Joshua; Que, Larry.

In: Angewandte Chemie - International Edition, Vol. 57, No. 30, 20.07.2018, p. 9387-9391.

Research output: Contribution to journalArticle

Rasheed, Waqas ; Draksharapu, Apparao ; Banerjee, Saikat ; Young, Victor G ; Fan, Ruixi ; Guo, Yisong ; Ozerov, M. ; Nehrkorn, Joscha ; Krzystek, J. ; Telser, Joshua ; Que, Larry. / Crystallographic Evidence for a Sterically Induced Ferryl Tilt in a Non-Heme Oxoiron(IV) Complex that Makes it a Better Oxidant. In: Angewandte Chemie - International Edition. 2018 ; Vol. 57, No. 30. pp. 9387-9391.
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AU - Banerjee, Saikat

AU - Young, Victor G

AU - Fan, Ruixi

AU - Guo, Yisong

AU - Ozerov, M.

AU - Nehrkorn, Joscha

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AB - Oxoiron(IV) units are often implicated as intermediates in the catalytic cycles of non-heme iron oxygenases and oxidases. The most reactive synthetic analogues of these intermediates are supported by tetradentate tripodal ligands with N-methylbenzimidazole or quinoline donors, but their instability precludes structural characterization. Herein we report crystal structures of two [FeIV(O)(L)]2+ complexes supported by pentadentate ligands incorporating these heterocycles, which show longer average Fe–N distances than the complex with only pyridine donors. These longer distances correlate linearly with log k2′ values for O- and H-atom transfer rates, suggesting that weakening the ligand field increases the electrophilicity of the Fe=O center. The sterically bulkier quinoline donors are also found to tilt the Fe=O unit away from a linear N-Fe=O arrangement by 10°.

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