Bidentate N-heterocyclic carbene precursors synthesis, study of their coordination chemistry and catalysis ; Préparation de précurseurs de carbènes N-hétérocycliques bidentes, étude de leur complexation et catalyse
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Media type:
E-Book
Title:
Bidentate N-heterocyclic carbene precursors synthesis, study of their coordination chemistry and catalysis ; Préparation de précurseurs de carbènes N-hétérocycliques bidentes, étude de leur complexation et catalyse
imprint:
[Erscheinungsort nicht ermittelbar]: HAL CCSD, 2007
Language:
French
Origination:
University thesis:
Dissertation, HAL CCSD, 2007
Footnote:
Description:
Advances in the search of highly efficient complexes for catalysis have led to an intensive use of N-heterocyclic carbenes (NHCs). In the last fifteen years, this kind of ligands has gained a lot of attention, in comparison to others, by their ability to give access to highly stable and highly active complexes. Recent studies on the synthesis of bidentates ligands bearing one NHC unit and a coordinating nitrogen, and their highly active complexes, have oriented us on the preparation of the similar ligands with others heteroatoms. As part of this newly developed theme in our group, we have prepared two original synthetic pathways leading to new N-heterocyclic carbene precursors, composed of an imidazolium group and another coordinating group which will be a phosphine or a thioether. The study of these ligands has enabled the development of a rich coordination chemistry with Ni, Pd, Rh, Ru and Ir. Four coordination modes have been shown: the coordination with only the heteroatom or the NHC, or a coordination of both the heteraoatom and NHC via a normal" mode or an "abnormal" mode. Our studies have shown that the coordination mode adopted by the ligands was correlated to the experimental conditions, the metal reactivity and its affinity for the heteroatom. The preparation of such complexes allowed us to carry out some preliminary tests in hydrosilylation and hydrogenation with rhodium(I) complexes. A thorough study of the coupling reaction of a Grignard reagent with an aryl halide (Kumada-Corriu-Tamao reaction) was undertaken with the nickel(II) complexes.