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Oxidation of Cyclohexane by High-Valent Iron Bispidine Complexes: Tetradentate versus Pentadentate Ligands
被引:75
作者:
Comba, Peter
[1
]
Maurer, Martin
[1
]
Vadivelu, Prabha
[1
]
机构:
[1] Heidelberg Univ, Inst Anorgan Chem, D-69120 Heidelberg, Germany
关键词:
NONHEME OXOIRON(IV) COMPLEXES;
DENSITY-FUNCTIONAL THERMOCHEMISTRY;
KETOGLUTARATE DIOXYGENASE TAUD;
OXYGEN ACTIVATION;
FE-IV=O;
SPECTROSCOPIC CHARACTERIZATION;
METAL-COMPLEXES;
EPOXIDATION;
INTERMEDIATE;
RADICALS;
D O I:
10.1021/ic901702s
中图分类号:
O61 [无机化学];
学科分类号:
070301 ;
081704 ;
摘要:
The iron-bispidine-catalyzed oxidation of cyclohexane with H2O2, where either a tetradentate or a pentadentate bispidine ligand is coordinated to the iron center, yields up to 35% cyclohexanol and cyclohexanone (alcohol/ketone ratio of up to 4). Product distribution (including O-18 labeling studies), kinetic isotope effects, and the ratio of tertiary/secondary alcohols with adamantane as a substrate (3 degrees/2 degrees) suggest that (i) H abstraction by a ferryl complex is the rate-determining step and that the emerging cyclohexyl radical is short-lived, (ii) there is a parallel reaction involving oxidation by OH radicals, and (iii) there are considerable differences in the reaction pathways between the tetradentate and pentadentate ligand catalyst. These interpretations are fully supported by a DFT-based computational analysis.
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页码:10389 / 10396
页数:8
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