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Direct Observation of Primary C−H Bond Oxidation by an Oxido‐Iron(IV) Porphyrin π‐Radical Cation Complex in a Fluorinated Carbon Solvent
Author(s) -
Morimoto Yuma,
Shimaoka Yuki,
Ishimizu Yuri,
Fujii Hiroshi,
Itoh Shinobu
Publication year - 2019
Publication title -
angewandte chemie international edition
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 5.831
H-Index - 550
eISSN - 1521-3773
pISSN - 1433-7851
DOI - 10.1002/anie.201901608
Subject(s) - porphyrin , solvent , primary (astronomy) , chemistry , photochemistry , radical ion , carbon fibers , medicinal chemistry , polymer chemistry , organic chemistry , materials science , ion , physics , astronomy , composite number , composite material
Oxido‐iron(IV) porphyrin π‐radical cation species are involved in a variety of heme‐containing enzymes and have characteristic oxidation states consisting of a high‐valent iron center and a π‐conjugated macrocyclic ligand. However, the short lifetime of the complex has hampered detailed reactivity studies. Reported herein is a remarkable increase in the lifetime (80 s at 10 °C) of Fe IV (TMP +. )(O)(Cl) ( 2 ; TMP=5,10,15,20‐tetramesitylporphyrin dianion), produced by the oxidation of Fe III (TMP)(Cl) ( 1 ) by ozone in α,α,α‐trifluorotoluene (TFT). The lifetime is 720 times longer compared to that of the currently most stable species reported to date. The increase in the lifetime improves the reaction efficiency of 2 toward inert alkane substrates, and allowed observation of the reaction of 2 with a primary C−H bond (BDE C‐H =ca. 100 kcal mol −1 ) directly. Activation parameters for cyclohexane hydroxylation were also obtained.