Pd(II) ‐catalyzed addition polymerizations of strained polycyclic olefins

Abstract

Abstract Cationic Pd(II) ‐complexes with weakly coordinating ligands were used for the olefin addition polymerization of strained polycyclic olefins. The cyclic structure of the monomers remained intact during the reaction which contrasts with products obtained from the olefin metathesis polymerization. The Pd(II) ‐catalyzed polymerizations showed the features of a “living” polymerization, when norbornene and selected exo‐substituted norbornene derivatives were used as the monomers. Endo ‐ and exo ‐dicyclopentadiene, exo ‐1,2‐dihydrodicyclopentadiene, endo, exo ‐1,4,5,8‐dimethano‐1,2,3,4,4a,5,8,8a‐octahydronaphthalene and endo, exo ‐1,4,5,8‐dimethano‐1,4,4,a,5,8,8a‐hexahydronaphthalene were converted into the corresponding rigid polymers. The exo‐substituted monomers were found to polymerize at a higher rate than the corresponding or similar endo‐substituted monomers. The polymerization of norbornadiene and the subsequent thermal elimination of cyclopentadiene resulted in the formation of polyacetylene.