Reference : Homobimetallic Ruthenium-Arene Complexes Bearing Vinylidene Ligands Synthesis, Charac...
Scientific journals : Article
Physical, chemical, mathematical & earth Sciences : Chemistry
Homobimetallic Ruthenium-Arene Complexes Bearing Vinylidene Ligands Synthesis, Characterization, and Catalytic Application in Olefin Metathesis
Borguet, Yannick mailto [Université de Liège - ULg > Département de chimie (sciences) > Chimie macromoléculaire et catalyse organique]
Sauvage, Xavier [Université de Liège - ULg > > Centre de recherches du cyclotron]
Zaragoza, Guillermo [> > > >]
Demonceau, Albert mailto [Université de Liège - ULg > Département de chimie (sciences) > Chimie macromoléculaire et catalyse organique]
Delaude, Lionel mailto [Université de Liège - ULg > Département de chimie (sciences) > Chimie macromoléculaire et catalyse organique >]
American Chemical Society
Yes (verified by ORBi)
[en] Five new arylvinylidene complexes with substituents ranging from electron donating to strongly withdrawing (p OMe p Me p Cl p CF3 and m (CF3)(2)) were isolated in high yields by reacting [(p cymene)Ru(mu Cl)(3)RuCl(eta(2) C2H4)(PCy3)] (3) with the corresponding phenylacetylene derivatives The known phenylvinylidene complex [(p cymene)Ru(mu Cl)(3)RuCl(=C=CHPh)(PCy3)] (5) was also obtained from [RuCl2(p cymene)](2) tricyclohexylphosphine and phenylacetylene under microwave irradiation The influence of the remote aryl substituents on structural features was investigated by IR NMR and XRD spectroscopes A very good linear relationship was observed between the chemical shift of the vinylidene alpha carbon atom and the Hammett sigma constants of the aryl group substituents The catalytic activity of the six homobimetallic complexes was probed in various types of olefin metathesis reactions Unsubstituted phenylvinylidene compound 5 served as a lead structure for these experiments Its reaction with norbornene afforded high molecular weight polymers with a broad polydispersity index and mostly trans double bonds Aluminum chloride was a suitable cocatalyst for the ring opening metathesis polymerization of cyclooctene and led to the formation of high molecular weight polyoctenamer with a rather narrow polydispersity index (M-w/M-n = 1 25) and an almost equimolar proportion of cis and trans double bonds No major changes were observed in the polymer yields and microstructures when complexes bearing donor groups on their aryl rings were employed as catalyst precursors On the other hand compounds bearing strongly electron withdrawing substituents were significantly less active Model vinylidene compound 5 and its ruthenium-ethylene parent (3) both required the addition of phenylacetylene to achieve the ring closing metathesis of diethyl 2 2 diallylmalonate Thus the role of this terminal alkyne cocatalyst goes beyond the facile replacement of the eta(2) alkene ligand with a vinylidene fragment
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