Département de chimie moléculaire

Herein we report the synthesis and single-crystal X-ray diffraction study of a cyclic diaminocarbene, which retains the nucleophilicity of classical N-heterocyclic carbenes (NHCs), but show enhanced electrophilicity. Our results demonstrate that the placement of one of the two nitrogen atoms of a NHC in a bridgehead position considerably increase the electrophilic character of the carbene center, without diminishing its nucleophilicity. Because a variety of bicyclic scaffolds are available, the pyramidalization of the bridgehead nitrogen atom can be modified at will. This simple topol. modification should allow the fine tuning of the $π$-accepting properties of NHCs, and consequently of the catalytic properties of the corresponding metal complexes. [on SciFinder(R)]