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Homoleptic Rhodium Pyridine Complexes for Catalytic Hydrogen Oxidation
Yu Zhang1, Toby J Woods1, Thomas B Rauchfuss1
1School of Chemical Sciences, University of Illinois at Urbana-Champaign, 600 South Goodwin Avenue, Urbana, Illinois 61801, United States.
Journal of the American Chemical Society
|June 28, 2021
Summary
Researchers developed a novel rhodium pyridine complex that activates hydrogen. This complex enables a new catalytic system for hydrogen oxidation using ferrocenium, paving the way for advanced catalysis.
Area of Science:
- Inorganic Chemistry
- Organometallic Chemistry
- Catalysis
Background:
- The homoleptic rhodium pyridine complex, [Rh(py)4]+ ([1]+), is synthesized from accessible starting materials.
- This complex is sterically shielded and lacks strong π-acceptor ligands, influencing its redox properties.
Purpose of the Study:
- To investigate the redox behavior and hydrogen activation capabilities of the [Rh(py)4]+ complex.
- To explore the potential of this complex in novel catalytic systems.
Main Methods:
- Preparation and characterization of the rhodium pyridine complex [Rh(py)4]+.
- Electrochemical studies to determine redox potentials and stability.
- Hydrogen activation experiments under various conditions.
- Catalytic studies using ferrocenium as an oxidant.
Main Results:
- The [Rh(py)4]+ complex reversibly oxidizes to a Rh(II) species, [Rh(py)4(thf)2]2+.
- The Rh(II) complex activates H2, forming a Rh(III)-hydride species, [HRh(py)4L]2+.
- The Rh(III)-H bond is labile, prone to hydrogen atom abstraction and deprotonation.
- A novel catalytic system for H2 oxidation using ferrocenium was established.
Conclusions:
- The rhodium pyridine complex [Rh(py)4]+ is a versatile precursor for hydrogen activation.
- The observed reactivity of the Rh(II) and Rh(III)-hydride species is key to the catalytic cycle.
- This work presents a new catalytic approach for hydrogen oxidation relevant to energy and chemical synthesis.
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