Trapping iron(III)-Oxo species at the boundary of the "oxo Wall": Insights into the nature of the Fe(III)-O bond

Erik Andris, Rafael Navrátil, Juraj Jašík, Mayank Puri, Miquel Costas, Lawrence Que, Jana Roithovaá

Research output: Contribution to journalArticle

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Abstract

Terminal non-heme iron(IV)-oxo compounds are among the most powerful and best studied oxidants of strong C-H bonds. In contrast to the increasing number of such complexes (>80 thus far), corresponding one-electron-reduced derivatives are much rarer and presumably less stable, and only two iron(III)-oxo complexes have been characterized to date, both of which are stabilized by hydrogen-bonding interactions. Herein we have employed gas-phase techniques to generate and identify a series of terminal iron(III)-oxo complexes, all without built-in hydrogen bonding. Some of these complexes exhibit ~70 cm-1 decrease in ν(Fe-O) frequencies expected for a half-order decrease in bond order upon one-electron reduction to an S = 5/2 center, while others have ν(Fe-O) frequencies essentially unchanged from those of their parent iron(IV)-oxo complexes. The latter result suggests that the added electron does not occupy a d orbital with Fe=O antibonding character, requiring an S = 3/2 spin assignment for the nascent FeIII-O- species. In the latter cases, water is found to hydrogen bond to the FeIII-O- unit, resulting in a change from quartet to sextet spin state. Reactivity studies also demonstrate the extraordinary basicity of these iron(III)-oxo complexes. Our observations show that metal-oxo species at the boundary of the "Oxo Wall" are accessible, and the data provide a lead to detect iron(III)-oxo intermediates in biological and biomimetic reactions.

Original languageEnglish (US)
Pages (from-to)14391-14400
Number of pages10
JournalJournal of the American Chemical Society
Volume140
Issue number43
DOIs
StatePublished - Jan 1 2019

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Iron
Hydrogen bonds
Electrons
Hydrogen Bonding
Biomimetics
Alkalinity
Oxidants
Hydrogen
Gases
Metals
Derivatives
Water
ferryl iron

PubMed: MeSH publication types

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

Cite this

Trapping iron(III)-Oxo species at the boundary of the "oxo Wall" : Insights into the nature of the Fe(III)-O bond. / Andris, Erik; Navrátil, Rafael; Jašík, Juraj; Puri, Mayank; Costas, Miquel; Que, Lawrence; Roithovaá, Jana.

In: Journal of the American Chemical Society, Vol. 140, No. 43, 01.01.2019, p. 14391-14400.

Research output: Contribution to journalArticle

Andris, Erik ; Navrátil, Rafael ; Jašík, Juraj ; Puri, Mayank ; Costas, Miquel ; Que, Lawrence ; Roithovaá, Jana. / Trapping iron(III)-Oxo species at the boundary of the "oxo Wall" : Insights into the nature of the Fe(III)-O bond. In: Journal of the American Chemical Society. 2019 ; Vol. 140, No. 43. pp. 14391-14400.
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