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High-Spin Iron Imido Complexes Competent for C-H Bond Amination
Matthew J T Wilding1, Diana A Iovan1, Theodore A Betley1
1Department of Chemistry and Chemical Biology, Harvard University , 12 Oxford Street, Cambridge, Massachusetts 02138, United States.
Journal of the American Chemical Society
|August 5, 2017
Summary
This study introduces a novel iron(I) complex as a versatile synthon. It reacts with azides to form high-spin iron imido complexes, enabling C-H bond functionalization and amination reactions.
Area of Science:
- Inorganic Chemistry
- Organometallic Chemistry
- Catalysis
Background:
- Iron complexes are crucial in catalysis and synthetic chemistry.
- Low-spin iron(I) synthons with unique electronic properties are valuable.
- Development of new iron complexes for C-H functionalization is an active research area.
Purpose of the Study:
- To synthesize and characterize a novel low-spin iron(I) complex.
- To investigate the reactivity of the iron(I) complex with organic azides.
- To explore the potential of the resulting iron imido complexes in C-H bond functionalization.
Main Methods:
- Synthesis of a low-spin iron(I) complex, (ArL)Fe, from (ArL)FeCl.
- Reaction of (ArL)Fe with adamantyl azide and mesityl azide to form iron imido complexes.
- Characterization using EPR, Mössbauer spectroscopy, magnetometry, and X-ray diffraction.
- Kinetic studies (kH/kD) to elucidate the C-H amination mechanism.
Main Results:
- A low-spin iron(I) complex, (ArL)Fe, featuring an intramolecular η6-arene interaction was synthesized.
- Treatment with azides yielded high-spin, three-coordinate iron imido complexes, (ArL)Fe(NAd) and (ArL)Fe(NMes).
- These iron imido complexes demonstrated reactivity including tetrazido formation, nitrene transfer, H-atom abstraction, and intermolecular C-H amination of toluene with significant kinetic isotope effects.
Conclusions:
- The synthesized iron(I) complex serves as an effective precursor for generating reactive iron imido species.
- The high-spin iron imido complexes exhibit diverse reactivity, particularly in C-H bond functionalization.
- A two-step mechanism involving maximal energy and orbital overlap is proposed for the C-H amination reactivity.
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