Unsymmetrically N,N'-substituted saturated carbenes: synthesis, reactivity and preparation of a rhodium(I) carbene complex
| Autor: | Duc Le Van, Roland Fröhlich, F. Ekkehardt Hahn, Martin Paas |
|---|---|
| Rok vydání: | 2006 |
| Předmět: |
chemistry.chemical_classification
Models Molecular Aldimine Magnetic Resonance Spectroscopy Ligand Transition metal carbene complex chemistry.chemical_element Nuclear magnetic resonance spectroscopy Medicinal chemistry Hydrocarbons Rhodium Inorganic Chemistry chemistry.chemical_compound Monomer chemistry Models Chemical X-Ray Diffraction Organic chemistry Reactivity (chemistry) Amines Carbene Dimerization Methane Sulfur |
| Zdroj: | Dalton transactions (Cambridge, England : 2003). (6) |
| ISSN: | 1477-9226 |
| Popis: | A versatile synthesis of unsymmetrically N,N′-substituted saturated carbenes is described. The novel racemic imidazolidin-2-ylidenes rac-5 have been synthesized by reductive desulfurization of the corresponding imidazolidin-2-thiones rac-4. The thiones were prepared in two reaction steps from aldimines and secondary amines. Three different substituents at N1, N3 and C4 of the five-membered N-heterocyclic ring can be introduced by choice of suitable aldimines and secondary amines. The dimerization behaviour (diaminocarbene/enetetramine equilibrium) for the unsymmetrically N,N′-substituted imidazolidin-2-ylidenes has been investigated by NMR spectroscopy. Unsymmetrically N–iPr and N–iBu substituted N-heterocyclic carbenes undergo a slow dimerization, whereas N–tBu substituted derivatives are stable as monomeric carbenes indefinitely. The carbene ligand rac-5d has been coordinated to rhodium(I) to give the square-planar rhodium carbene complex [Cl(cod)Rh(rac-5d)] rac-6d which has been characterized by an X-ray diffraction analysis. |
| Databáze: | OpenAIRE |
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