Universität Heidelberg, Anorganisch-Chemisches Institut, INF 270, 69120 Heidelberg, Germany.
Chemistry. 2010 Jun 25;16(24):7293-9. doi: 10.1002/chem.201000092.
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), tBuOOH, or iodosylbenzene, the high-valent Fe=O 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 C-H 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.
当双核铁(II)配合物的四齿双吡啶配体 L=3,7-二甲基-9-氧代-2,4-二(2-吡啶基)-3,7-二氮杂双环[3.3.1]壬烷-1,5-二羧酸甲酯用 H(2)O(2)、tBuOOH 或碘苯氧化时，高价 Fe=O 配合物可有效地氧化和卤化环己烷。动力学 D 同位素效应和对叔碳上氢原子（在金刚烷的卤化中定量）的优先取代的偏好表明，C-H 活化是速率决定步骤。效率（化学计量和催化反应的周转率中的产率）、产物比（醇与溴代烷和氯代烷）和动力学同位素效应取决于氧化剂。这些结果表明不同的氧化剂有不同的途径，这些途径可能包括铁(IV)-和铁(V)-氧配合物以及基于氧的自由基。
