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 [(Cp2TiCH3)-C-13](+)[Cl . MAO](-) and of precursors of alkylidene Cp2Ti=CH2 species in addition alkene polymerization, (ii) the synthetical strategies for converting the living active titanacyclobutanes into sigma-titanocene complexes, and (iii) the evidence for the synthesis of polyethylene polynorbornene di-block copolymer are briefly summarized. C-13 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. (C) 1998 Elsevier Science B.V. All rights reserved.