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10:51
The Synthesis, Characterization and Reactivity of a Series of Ruthenium N-triphosPh Complexes
Published on: April 10, 2015
Mononuclear ruthenium(II) complexes that catalyze water oxidation
Huan-Wei Tseng1, Ruifa Zong, James T Muckerman
1Department of Chemistry, University of Houston, 136 Fleming Building, Houston, Texas 77204-5003, USA.
Inorganic Chemistry
|November 14, 2008
Summary
Ruthenium complexes with polypyridine ligands efficiently catalyze water oxidation. A proposed mechanism involves a seven-coordinate ruthenium(VI) species, supported by DFT calculations.
Area of Science:
- Inorganic Chemistry
- Catalysis
- Photochemistry
Background:
- Water oxidation is crucial for artificial photosynthesis and renewable energy.
- Developing efficient and stable catalysts for water oxidation is a key challenge.
- Ruthenium complexes are promising candidates due to their tunable electronic properties.
Purpose of the Study:
- To synthesize and characterize two series of mononuclear ruthenium(II) complexes with polypyridine ligands.
- To evaluate the catalytic activity of these complexes in water oxidation.
- To elucidate the mechanism of water oxidation catalyzed by these ruthenium complexes.
Main Methods:
- Synthesis of [Ru(tpy)(NN)Cl](PF6) and other ruthenium complexes with varying polypyridine ligands.
- Spectroscopic (UV-Vis) and electrochemical (redox potentials) characterization.
- Water oxidation catalytic activity testing and kinetic measurements.
- Density Functional Theory (DFT) calculations.
Main Results:
- 23 ruthenium complexes were prepared and characterized.
- 14 of the complexes demonstrated catalytic activity for water oxidation, with those containing terpyridine (tpy) or dipyridylphenanthroline (dpp) being most effective.
- Kinetic studies indicated a first-order reaction and ruled out ruthenium dioxide (RuO2) involvement.
- Electronic and redox properties correlated well with complex structure.
Conclusions:
- Ruthenium complexes featuring terpyridine or dipyridylphenanthroline ligands are effective water oxidation catalysts.
- A mechanism involving a seven-coordinate Ru(VI)=O intermediate is proposed for O-O bond formation.
- DFT calculations support the proposed catalytic mechanism.
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