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Updated: May 8, 2026
10:39
Heterogeneous Removal of Water-Soluble Ruthenium Olefin Metathesis Catalyst from Aqueous Media Via Host-Guest Interaction
Published on: August 23, 2018
Evidence for Direct trans Insertion in a Hydrido-Olefin Rhodium Complex-Free Nitrogen as a Trap in a Migratory
A Vigalok1, H B Kraatz, L Konstantinovsky
1Department of Organic Chemistry, The Weizmann Institute of Science Rehovot 76100 (Israel),
Chemistry (Weinheim an Der Bergstrasse, Germany)
|September 12, 2013
Summary
Reduction of a rhodium complex yields dinitrogen and hydrido-olefin complexes in equilibrium. The dinitrogen complex is more stable, and its dissociation is the rate-limiting step for interconversion.
Area of Science:
- Organometallic Chemistry
- Coordination Chemistry
- Catalysis
Background:
- Rhodium complexes are vital in catalysis.
- Understanding ligand and metal interactions is key to designing efficient catalysts.
- Low-valent rhodium hydrido complexes exhibit unique reactivity.
Purpose of the Study:
- To investigate the formation and interconversion of dinitrogen and hydrido-olefin rhodium complexes.
- To elucidate the mechanism of reversible interconversion between these complexes.
- To determine the thermodynamic and kinetic parameters governing the equilibrium.
Main Methods:
- Synthesis and characterization of rhodium complexes.
- X-ray crystallography to determine solid-state structures.
- Variable-temperature Nuclear Magnetic Resonance (NMR) spectroscopy, including saturation transfer experiments, to study reaction mechanisms and kinetics.
Main Results:
- Two rhodium complexes, a dinitrogen complex (2) and a hydrido-olefin complex (3), were formed and found to be in equilibrium.
- Complex 2 is thermodynamically more stable than complex 3 plus dinitrogen.
- The interconversion mechanism involves olefin insertion/β-hydrogen elimination in complex 3 and dinitrogen dissociation from complex 2 as the rate-determining step.
Conclusions:
- The study reveals a novel equilibrium between dinitrogen and hydrido-olefin rhodium complexes.
- The mechanism highlights the role of ligand structure and metal coordination in facilitating unusual reaction pathways like concerted "trans migration".
- Dinitrogen dissociation is identified as the bottleneck for the overall interconversion process.
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