Resumen de Versatilidad coordinativa de carbenos N-heterocíclicos. Diseño de ligandos con nuevas topologías y coordinación a Rh, Ir y Mo: estudio de las propiedades catalíticas
N-Heterocyclic carbene ligands (NHC), first coordinated to a metal center by Öfele and Wanzlick in 1968 and later isolated in the free state by Arduengo, have emerged as promising ligands for the design of new homogeneous catalysts.
N-Heterocyclic carbene ligand One of the main reasons why these ligands have been so widely used in catalyst design during the last decade, is that their steric and electronic properties can be easily modulated, mainly due to their relatively simple preparation and the extraordinary high variety of cheap commercial precursors that can be found from the ordinary chemical suppliers. Polydentate NHC ligands has allowed the preparation of new compounds whose stability is entropically improved by the chelate effect.. Not only chelating bis-NHCs are yielding more stable metal complexes, but they are also providing interesting features that can provide fine tuning of topological properties such as steric hindrance, bite angles, chirality and fluxional behavior.
With all this in mind, the present work deals with the study of the coordinative versatility of NHC ligands, by designing new coordination topologies and coordination strategies, and by extending their coordination to early transition metals in high oxidation states. The catalytic activities of the complexes obtained in standard reactions are also described, and the results are compared to other complexes containing other classical ligands.
