Cyclic olefin polymerization and relationships between addition and ring opening metathesis polymerization

Results of our work concerning: i the elucidation of the role of the ionic species Cp Ti CH ClPMAO and of 2 3 precursors of alkylidene Cp Ti5CH species in addition alkene polymerization, ii the synthetical strategies for converting . 2 2 the living active titanacyclobutanes into s-titanocene complexes, and iii the evidence for the synthesis of polyethylene . polynorbornene di-block copolymer are briefly summarized. 13C NMR spectra of ethylene-norbornene copolymers, prepared with addition catalysts based on ansa-zirconocenes and methylaluminoxane as cocatalyst, and assignments of comonomer pentads in ethylene-norbornene EN copolymers are reported. . q1998 Elsevier Science B.V. All rights reserved.