RING-OPENING POLYMERIZATION OF ENDO AND EXO-DICYCLOPENTADIENE AND THEIR 7,8-DIHYDRO DERIVATIVES

A range of metathesis catalysts have been used to prepare polymers from the title monomers. The fraction of cis double bonds, sigma //c, in the polymers was determined by **1**3C NMR spectroscopy. The spectra of polymers containing mainly cis or trans double bonds in the main chain, as well as polymers derived from these by hydrogenation, were analyzed in detail in terms of orientational and tacticity effects. With endo-dicyclopentadiene, the catalyst RuCl//3 multiplied by (times) 3H//2O produced a high-cis polymer. This anomalous results is believed to be due to a steric effect at the catalyst site caused by endo-dicyclopentadiene also acting as a permanent ligand because of its unique potential, among these monomers, to chelate in a bidentate fashion.