Non-heme-iron-mediated selective halogenation ofuUnactivated carbon-hydrogen bonds

• Verfasst von: Bleher, Katharina [VerfasserIn]
• Verfasst von: Comba, Peter [VerfasserIn]
• Verfasst von: Faltermeier, Dieter [VerfasserIn]
• Verfasst von: Gupta, Ashutosh [VerfasserIn]
• Verfasst von: Kerscher, Marion [VerfasserIn]
• Verfasst von: Krieg, Saskia [VerfasserIn]
• Verfasst von: Martin, Bodo [VerfasserIn]
• Verfasst von: Velmurugan, Gunasekaran [VerfasserIn]
• Verfasst von: Yang, Shuyi [VerfasserIn]
• Titel: Non-heme-iron-mediated selective halogenation ofuUnactivated carbon-hydrogen bonds
• Verf.angabe: Katharina Bleher, Peter Comba, Dieter Faltermeier, Ashutosh Gupta, Marion Kerscher, Saskia Krieg, Bodo Martin, Gunasekaran Velmurugan, and Shuyi Yang
• Jahr: 2022
• Umfang: 9 S.
• Fussnoten: Gesehen am 04.01.2023
• Titel Quelle: Enthalten in: Chemistry - a European journal
• Ort Quelle: Weinheim : Wiley-VCH, 1995
• Jahr Quelle: 2022
• Band/Heft Quelle: 28(2022), 4, Artikel-ID e202103452, Seite 1-9
• ISSN Quelle: 1521-3765
• DOI: doi:10.1002/chem.202103452
• Datenträger: Online-Ressource
• Sprache: eng
• Sach-SW: biomimetic coordination chemistry
• Sach-SW: C−H activation
• Sach-SW: DFT calculations
• Sach-SW: non-heme-iron
• Sach-SW: reaction mechanism
• K10plus-PPN: 183035566X
• K10plus-PPN:
  Universitätsbibliothek
• Lokale URL UB: Zum Volltext

Abstract

Oxidation of the iron(II) precursor [(L1)FeIICl2], where L1 is a tetradentate bispidine, with soluble iodosylbenzene (sPhIO) leads to the extremely reactive ferryl oxidant [(L1)(Cl)FeIV=O]+ with a cis disposition of the chlorido and oxido coligands, as observed in non-heme halogenase enzymes. Experimental data indicate that, with cyclohexane as substrate, there is selective formation of chlorocyclohexane, the halogenation being initiated by C−H abstraction and the result of a rebound of the ensuing radical to an iron-bound Cl−. The time-resolved formation of the halogenation product indicates that this primarily results from sPhIO oxidation of an initially formed oxido-bridged diiron(III) resting state. The high yield of up to >70 % (stoichiometric reaction) as well as the differing reactivities of free Fe2+ and Fe3+ in comparison with [(L1)FeIICl2] indicate a high complex stability of the bispidine-iron complexes. DFT analysis shows that, due to a large driving force and small triplet-quintet gap, [(L1)(Cl)FeIV=O]+ is the most reactive small-molecule halogenase model, that the FeIII/radical rebound intermediate has a relatively long lifetime (as supported by experimentally observed cage escape), and that this intermediate has, as observed experimentally, a lower energy barrier to the halogenation than the hydroxylation product; this is shown to primarily be due to steric effects.