Addition polymerization of functionalized norbornenes: The effect of size, stereochemistry, and coordinating ability of the substituent

The effect of the substituent on the palladium(II)-catalyzed addition polymerization of functionalized norbornene derivatives was examined. Endo-substituted norbornenes are polymerized more slowly than their corresponding exo isomers. The size of the substituent plays a role. However, the coordinating ability of the functionality plays an even bigger role in attenuating polymerization than its size. The formation of chelates upon the coordination of the endo-functionalized norbornene is responsible, in part, for the observed decrease in polymerization rate. A further, and even greater, reason for the diminution of activity of both the endo- and the exo-functionalized isomers is simply the coordination of the functionality to the metal center.