PD(II)-CATALYZED ADDITION POLYMERIZATIONS OF STRAINED POLYCYCLIC OLEFINS

Cationic Pd(II)-complexes with weakly coordinating ligands were used f or the olefin addition polymerization of strained polycyclic olefins. The cyclic structure of the monomers remained intact during the reacti on which contrasts with products obtained from the olefin metathesis p olymerization. The Pd(II)-catalyzed polymerizations showed the feature s of a ''living'' polymerization, when norbornene and selected exo-sub stituted norbornene derivatives were used as the monomers. Endo- and e xo-dicyclopentadiene, exo-1,2-dihydrodicyclopentadiene, 8-dimethano-1, 2,3,4,4a,5,8,8a-octahydronaphthalene and endo,exo-1,4,5,8-dimethano-1, 4,4,a,5,8,8 naphthalene were converted into the corresponding rigid po lymers. The exo-substituted monomers were found to polymerize at a hig her rate than the corresponding or similar endo-substituted monomers. The polymerization of norbornadiene and the subsequent thermal elimina tion of cyclopentadiene resulted in the formation of polyacetylene.