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Solvent-Dependent Carbon-to-Metal Hydrogen Atom Transfer Reactivity of a Square Planar Rhodium(II) Alkynyl Complex
Thomas M Hood1, Sophie H Dewick1, Anjali John1
1Department of Chemistry, University of Warwick, Coventry CV4 7AL, U.K.
Organometallics
|April 17, 2026
Summary
This study details the synthesis of a rhodium-II alkynyl complex and its conversion to a vinylidene derivative. EPR spectroscopy and computational analysis confirm its metal-centered radical nature and reaction mechanism.
Area of Science:
- Organometallic Chemistry
- Coordination Chemistry
- Spectroscopy
Background:
- Square planar rhodium(II) complexes are key intermediates in catalysis.
- Understanding the reactivity of metal-centered radicals is crucial for mechanistic studies.
Purpose of the Study:
- To synthesize and characterize a novel rhodium(II) alkynyl complex.
- To investigate its transformation into a vinylidene derivative.
- To elucidate the reaction mechanism using computational and experimental methods.
Main Methods:
- Synthesis of [Rh-(PNP-tBu)-(C≡C-tBu)]+ and its vinylidene derivative.
- Reaction with 9,10-dihydroanthracene to study transformation.
- Electron Paramagnetic Resonance (EPR) spectroscopy for solid-state and solution studies.
- Multireference CAS-(9,6)/NEVPT2 calculations for mechanistic insights.
Main Results:
- The rhodium(II) alkynyl complex was synthesized and characterized as a metal-centered radical.
- The complex transforms into a vinylidene derivative via a proposed carbon-to-metal hydrogen atom transfer and 1,3-hydride migration mechanism.
- Square pyramidal solvent adducts were observed in frozen glass solutions.
- Solvent coordination inversely correlates with the reaction rate with 9,10-dihydroanthracene.
Conclusions:
- The study provides experimental and computational evidence for the mechanism of vinylidene formation from a rhodium(II) alkynyl complex.
- The metal-centered radical character and solvent effects on reactivity were elucidated.
- This work contributes to the understanding of organorhodium chemistry and reaction pathways.
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