New Pd–NHC-complexes for the Mizoroki–Heck reaction (original) (raw)

2007, Journal of Organometallic Chemistry

The synthesis and structural characterization of novel chelating N-aryl substituted palladium(II)-biscarbene-complexes is reported: 1,1 0 -bis(4-bromophenyl)-3,3 0 -methylene-diimidazoline-2,2 0 -diylidene-palladium(II)-dibromide, 1,1 0 -bis(4-methoxyphenyl)-3,3 0 -methylenediimidazoline-2,2 0 -diylidene-palladium(II)-dibromide and 1,1 0 -bis(4-n-butoxyphenyl)-3,3 0 -methylenediimidazoline-2,2 0 -diylidene-palladium(II)-dibromide have been synthesized in good yields. The catalytic activity of these 1,1 0 -aryl-3,3 0 -methylenediimidazoline-2, 2 0 -diylidene-palladium(II)-dihalogenide complexes was tested for the Mizoroki-Heck reaction in comparison to 1,1 0 -(bis)methyl-3, 3 0 -methylenediimidazoline-2,2 0 -diylidene-palladium(II)-dihalogenide complexes and to 1,1 0 -bis(phenyl)-3,3 0 -methylene-diimidazoline-2,2 0 -diylidene-palladium(II)-dibromide. The activity of the aryl substituted catalysts is significantly higher compared to the methyl substituted NHC complexes. They also allow the coupling of arylchlorides with olefins.