Catalytic Nitrene Transfer by an FeIV‐Imido Complex Generated by a Comproportionation Process

Nitrene transfer reactions have emerged as one of the most powerful and versatile ways to insert an amine function to various kinds of hydrocarbon substrates. However, the mechanisms of nitrene generation have not been studied in depth albeit their formation is taken for granted in most cases withou...

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Bibliographic Details
Published in:Chemistry : a European journal 2022-12, Vol.28 (70), p.e202201875-n/a
Main Authors: Donat, Jordan, Dubourdeaux, Patrick, Clémancey, Martin, Rendon, Julia, Gervasoni, Clara, Barbier, Morgan, Barilone, Jessica, Pécaut, Jacques, Gambarelli, Serge, Maldivi, Pascale, Latour, Jean‐Marc
Format: Article
Language:English
Subjects:
Catalysis
Chemical Sciences
Computer Science
Coordination chemistry
Cyclohexane
density functional calculations
Ethylbenzene
iron
nitrene transfer
or physical chemistry
Precursors
Species
spectroscopy
Styrene
Substrates
tetracarbene macrocycles
Theoretical and
Thioanisole
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Summary:Nitrene transfer reactions have emerged as one of the most powerful and versatile ways to insert an amine function to various kinds of hydrocarbon substrates. However, the mechanisms of nitrene generation have not been studied in depth albeit their formation is taken for granted in most cases without definitive evidence of their occurrence. In the present work, we compare the generation of tosylimido iron species and NTs transfer from FeII and FeIII precursors where the metal is embedded in a tetracarbene macrocycle. Catalytic nitrene transfer to reference substrates (thioanisole, styrene, ethylbenzene and cyclohexane) revealed that the same active species was at play, irrespective of the ferrous versus ferric nature of the precursor. Through combination of spectroscopic (UV‐visible, Mössbauer), ESI‐MS and DFT studies, an FeIV tosylimido species was identified as the catalytically active species and was characterized spectroscopically and computationally. Whereas its formation from the FeII precursor was expected by a two‐electron oxidative addition, its formation from an FeIII precursor was unprecedented. Thanks to a combination of spectroscopic (UV‐visible, EPR, Hyscore and Mössbauer), ESI‐MS and DFT studies, we found that, when starting from the FeIII precursor, an FeIII tosyliodinane adduct was formed and decomposed into an FeV tosylimido species which generated the catalytically active FeIV tosylimide through a comproportionation process with the FeIII precursor. An FeIV imide of a tetracarbene macrocycle active in nitrene transfer reactions can be generated from phenyltosyliodinane (PhI=NTs) either from the FeII precursor by oxidative addition (right) or from the FeIII precursor by a comproportionation reaction (left) (AN=acetonitrile, bold horizontal bars=macrocycle).
ISSN:0947-6539
1521-3765
DOI:10.1002/chem.202201875