Hydrooligomerization of cycloolefins -a view of the microstructure of polynorbornene

Abstract Hydrooligomerizations of norbornene were carried out using C 2 , C s and C 2 v symmetric zirconocenes with methylaluminoxane as catalysts. The structures of the hydrodimers and -trimers were investigated and correlated to the symmetry of the metallocene. The polymerization of norbornene is shown to proceed by cis-exo insertion. The mechanisms of polymerization and stereocontrol are closely related to the ones observed in the polymerization of α-olefins. Thus the C 2 symmetric metallocene features erythrodiisotactic structures, while erythrodisyndiotactic products are observed in case of the C s symmetric one. This is caused by enantiomorphic site control, while stereospecificity in the hydrooligomerization using Cp 2 ZrCl 2 MAO is determined by chain end control mechanism.