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Mizoroki-Heck Cross-coupling Reactions Catalyzed by Dichloro{bis[1,1',1''-(phosphinetriyl)tripiperidine]}palladium Under Mild Reaction Conditions
Published on: March 20, 2014
Bimetallic redox synergy in oxidative palladium catalysis
David C Powers1, Tobias Ritter
1Department of Chemistry and Chemical Biology, Harvard University, 12 Oxford Street, Cambridge, Massachusetts 02138, USA.
Accounts of Chemical Research
|October 28, 2011
Summary
Binuclear palladium complexes enable novel carbon-heteroatom bond formation through synergistic redox chemistry. This bimetallic approach offers advantages over traditional mononuclear catalysis for complex molecule synthesis.
Area of Science:
- Organometallic Chemistry
- Catalysis
- Oxidation Reactions
Background:
- Nature utilizes polynuclear transition metal complexes for oxidation reactions unmatched in the lab.
- Homogeneous catalysis has largely focused on mononuclear transition metal complexes.
- Developing new carbon-heteroatom bond-forming reactions is crucial for complex molecule synthesis.
Purpose of the Study:
- To investigate the redox chemistry of binuclear palladium complexes.
- To explore the role of binuclear intermediates in palladium-catalyzed oxidation reactions.
- To determine if bimetallic redox chemistry can lower activation barriers for catalytic transformations.
Main Methods:
- Stoichiometric organometallic studies of binuclear Pd(II) to Pd(III) oxidation.
- Analysis of C-X reductive elimination from binuclear Pd(III) complexes.
- Examination of metal-metal bond formation and its effect on oxidation barriers.
- Investigation of ligand modification effects on binuclear Pd(III) complex structure and reactivity.
- Comparison of bimetallic Pd(III) and monometallic Pd(IV) redox catalysis through experimental and theoretical work.
Main Results:
- Oxidation of binuclear Pd(II) to Pd(III) complexes and subsequent C-X reductive elimination confirm viability for C-X bond formation.
- Metal-metal bond formation concurrently with Pd(II) oxidation lowers the activation barrier for oxidation.
- Redox cooperation between metals in binuclear Pd(III) complexes facilitates C-X reductive elimination.
- Ligand modification significantly impacts the structure and reactivity of binuclear Pd(III) complexes.
- Bimetallic Pd(III) catalysis enables reactivity distinct from monometallic catalysts.
Conclusions:
- Bimetallic palladium complexes can effectively mediate carbon-heteroatom bond-forming reactions.
- Synergistic redox activity in binuclear palladium systems lowers activation barriers for key catalytic steps.
- Understanding bimetallic Pd(III) redox catalysis provides a platform for developing new catalytic reactions beyond monometallic approaches.
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