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Cobalt-carbene complex with single-bond character: intermediate for the cobalt complex-catalyzed cyclopropanation
Taketo Ikeno1, Izumi Iwakura, Tohru Yamada
1Department of Chemistry, Keio University, Hiyoshi, Kohoku-ku, Yokohama 223-8522, Japan.
Journal of the American Chemical Society
|December 19, 2002
Summary
The cobalt-carbene bond in salen-cobalt-carbene complexes is a single bond, challenging the double-bond assumption for cyclopropanation catalysts. This finding impacts the understanding of carbene complex reactivity.
Area of Science:
- Organometallic Chemistry
- Catalysis
- Spectroscopy
Background:
- Metal-carbene carbon bonds in cyclopropanation catalysts are typically assumed to be double bonds.
- This assumption influences the design and understanding of catalytic reactions involving carbene complexes.
Purpose of the Study:
- To investigate the precise nature of the cobalt-carbene carbon bond in specific salen-cobalt-carbene complexes.
- To challenge the prevailing assumption regarding the bond order in these catalytic systems.
Main Methods:
- Theoretical calculations (e.g., Density Functional Theory).
- Fourier-Transform Infrared (FT-IR) spectroscopy analysis.
Main Results:
- The cobalt-carbene carbon bond in 3-oxobutylideneaminato and salen-cobalt-carbene complexes was characterized as a single bond.
- This contradicts the widely held belief of a double bond in such complexes.
Conclusions:
- The cobalt-carbene bond in these complexes is predominantly single, not double.
- This finding necessitates a re-evaluation of the electronic structure and reactivity models for salen-cobalt-carbene catalysts in cyclopropanation.
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