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Iron‐Catalyzed Halogenation of Alkanes: Modeling of Nonheme Halogenases by Experiment and DFT Calculations
Author(s) -
Comba Peter,
Wunderlich Steffen
Publication year - 2010
Publication title -
chemistry – a european journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.687
H-Index - 242
eISSN - 1521-3765
pISSN - 0947-6539
DOI - 10.1002/chem.201000092
Subject(s) - chemistry , halogenation , catalysis , kinetic isotope effect , cyclohexane , adamantane , nonane , medicinal chemistry , hydrogen atom abstraction , ligand (biochemistry) , radical , organic chemistry , deuterium , biochemistry , physics , receptor , quantum mechanics
When the dichloroiron(II) complex of the tetradentate bispidine ligand L=3,7‐dimethyl‐9‐oxo‐2,4‐bis(2‐pyridyl)‐3,7‐diazabicyclo[3.3.1]nonane‐1,5‐dicarboxylate methyl ester is oxidized with H 2 O 2 , t BuOOH, or iodosylbenzene, the high‐valent FeO complex efficiently oxidizes and halogenates cyclohexane. Kinetic D isotope effects and the preference for the abstraction of tertiary over secondary carbon‐bound hydrogen atoms (quantified in the halogenation of adamantane) indicate that CH activation is the rate‐determining step. The efficiencies (yields in stoichiometric and turnover numbers in catalytic reactions), product ratios (alcohol vs. bromo‐ vs. chloroalkane), and kinetic isotope effects depend on the oxidant. These results suggest different pathways with different oxidants, and these may include iron(IV)– and iron(V)–oxo complexes as well as oxygen‐based radicals.