THE POLYMERIZATION OF SUPERIOR CYCLOOLEFI NES

In order to obtain more stereochemical data oil cycloolefin ring-openi ng polymerization, we studied the reaction of cyclopentene, cycloocten e, cyclododecene with the following catalytic systems: WCl6/iBu(3)Al/e pichlorohydrin, WCl6/iBu(3)Al/chloranyle, WCl6/SnPh(4), WCl6/Allyl(4)S i, WCl6/iBu(2) AlOAl iBu(2) The microstructure of the polyalkenamers w as determined by H-1- and C-13 -NMR spectroscopy. An important observa tion is that while cyclopentene polymerization displays a characterist ic stereospecificity dependent on catalyst nature or reaction temperat ure, the stereochemistry of the reaction of higher cycloolefins is det ermined strongly by the nature of monomer. The kinetic data and polyme r structure are discussed taking into account the role played by monom er conformation and the nature of the catalyst. A metallacarbene-metal lacyclobutane mechanism is advanced including different coordination w ays of the cycloolefins as a function of their size and conformation a nd variable oxidation slate of the catalyst.