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A Pseudotetrahedral Terminal Oxoiron(IV) Complex: Mechanistic Promiscuity in C−H Bond Oxidation Reactions
Author(s) -
Warm Katrin,
Paskin Alice,
Kuhlmann Uwe,
Bill Eckhard,
Swart Marcel,
Haumann Michael,
Dau Holger,
Hildebrandt Peter,
Ray Kallol
Publication year - 2021
Publication title -
angewandte chemie
Language(s) - English
Resource type - Journals
eISSN - 1521-3757
pISSN - 0044-8249
DOI - 10.1002/ange.202015896
Subject(s) - chemistry , steric effects , reactivity (psychology) , stereochemistry , ligand (biochemistry) , kinetic isotope effect , trigonal bipyramidal molecular geometry , catalysis , reactive intermediate , deuterium , crystallography , crystal structure , organic chemistry , medicine , biochemistry , physics , alternative medicine , receptor , pathology , quantum mechanics
S= 2 oxoiron(IV) species act as reactive intermediates in the catalytic cycle of nonheme iron oxygenases. The few available synthetic S =2 Fe IV =O complexes known to date are often limited to trigonal bipyramidal and very rarely to octahedral geometries. Herein we describe the generation and characterization of an S =2 pseudotetrahedral Fe IV =O complex 2 supported by the sterically demanding 1,4,7‐tri‐ tert ‐butyl‐1,4,7‐triazacyclononane ligand. Complex 2 is a very potent oxidant in hydrogen atom abstraction (HAA) reactions with large non‐classical deuterium kinetic isotope effects, suggesting hydrogen tunneling contributions. For sterically encumbered substrates, direct HAA is impeded and an alternative oxidative asynchronous proton‐coupled electron transfer mechanism prevails, which is unique within the nonheme oxoiron community. The high reactivity and the similar spectroscopic parameters make 2 one of the best electronic and functional models for a biological oxoiron(IV) intermediate of taurine dioxygenase (TauD‐ J ).