The first acyclic persistent carbene was reported in 1996, ..
metal carbene dimerization has been used in the synthesis of ..
We are fascinated by the diversity of effects that ligands can have to instigate new properties in transition metal complexes and we are therefore strongly interested in designing and developing new ligands that impart specific properties to the metal center. One of these ligands are triazolylidenes, a mesoionic carbene that we discovered in 2008. This ligand offers various opportunities for catalysis, including strong electron donor properties, a high synthetic flexibility that allows for a wide variety of functional and chelating groups to be incorporated, and a high polarity, which imparts solubility in water and other polar media. We have obtained evidence in a variety of catalytic reactions like nickel-catalysed hydrosilylation, ruthenium-catalyzed alcohol dehydrogenation, or iridium-catalyzed water oxidation, that the triazolylidene ligand scaffold is controlling the reactivity of the coordinated metal center. Because of the synthetic versatility and the easy accessibility of the ligand, tailoring of the ligand properties is straightforward and we have disclosed improved catalytic activity by ligand tuning. More recently, we have discovered a straightforward approach to functionalize the ligand on the complex as opposed to the more traditional approach of preparing a functional ligand and only then install the metal center. This approach gives rapid access to a large diversity of functionalized ligands in a very last step, and to ligand scaffolds that are not accessible by traditional routes.
the formulae L n MCRR' are often described as carbene ..
De introductie van een stikstof fragment op de vleugeltip van het NHC ligand, voor de supramoleculaire koppelingsstrategie van de katalysator en FS, slaagde niet.
N-Heterocyclic carbenes (NHCs) were ..
AB - N-Heterocyclic carbenes (NHCs) are valuable ligands in transition metal catalysis, due to their unique electronic properties. However, only a few routes toward unsymmetrically substituted, saturated NHCs are known. We have successfully applied the multicomponent synthesis of 2H-2-imidazolines for the preparation of a range of diversely substituted imidazolidin-2-ylidene complexes under mild conditions. In the desired NHC precursors the substituents at N-1, N-3, C-4, and C-5 were varied easily and independently by choosing the appropriate amine, aldehyde, isocyanide, or halide as starting material. Subsequent formation of the imidazolium salts followed by deprotonation with KO