POLYMERIZATION OF CYCLOPENTENE USING METALLOCENE CATALYSTS - POLYMER TACTICITY AND PROPERTIES

Hydro-oligomerization or polymerization of cyclopentene using racemic 1,2-ethylenebis(eta5-indenyl)zirconium dichloride (1) and methylaluminoxane leads to the production of poly(cis-1,3-cyclopentane) in which individual monomer units are incorporated in an isotactic manner. This was ultimately demonstrated through independent synthesis of the single, stereoisomeric tetramer produced under hydro-oligomerization conditions. In contrast to these result, hydro-oligomerization of cyclopentene with racemic 1,2-ethylenebis(eta5-tetrahydroindenyl)zirconium dichloride (5) led to the production of oligomers in which cyclopentene is incorporated in a cis- and trans-1,3 manner. This was also confirmed through independent synthesis of some of these saturated oligomers. A mechanism is proposed to account for the isotactic insertion of cyclopentene and the formation of the various hydro-oligomers produced.