THE ROLE OF 2-COMPONENT CATALYSTS CONTAINING CHELATING BISARYLOXIDE LIGANDS IN CONTROLLING THE STEREOCHEMISTRY OF THE METATHESIS POLYMERIZATION OF NORBORNENE

The ring-opening metathesis polymerization of norbornene and 5,5-dimethylnorbornene has been studied with a range of tungsten(VI) ring-opening metathesis polymerization procatalysts containing chelating diolate ligands, including catechols, 1,8-dihydroxynaphthalene, 1,1'-bi-2-naphthol, biphenanthrol and bis(2-hydroxyphenyl) methane. One class of these catalysts, W(=X)(OArO)Cl2(THF) (X = O or NArMe2) was produced via alcoholysis reactions between W(=X)Cl4 and the respective diol. Polymers of norbornene produced with these catalysts showed a reasonable correlation between ring size and cis-selectivity. This effect is most likely steric in origin. Analyses of the tacticity of poly-5,5-dimethylnorbornene showed a correlation between high cis-olefin content and syndiotacticity, even when produced with catalysts containing asymmetric chelating diolate ligands.