Ethylene norbornene copolymerizations with titanium CpA catalysts

Group 4 ansa-cyclopentadienylamido (CpA) complexes [Me2Si(Cp')(NR)]MCl2 (R = alkyl, M = Ti, Zr) efficiently copolymerize ethylene with a variety of al pha-olefins. Ethylene/norbornene copolymerization reactivity ratios mere de termined at 40 degrees C for CpA catalysts [Me2Si(Cp')((NBu)-Bu-t)]TiCl2 (C p' = Me4Cp, 2,4-Me2Cp, 3-(BuCp)-Bu-t, Ind), and the resulting values are lo w (r(1) = 2.0-5.1, r(2) --> 0), suggesting a tendency toward alternating co monomer insertion at high norbornene/ethylene feed ratios. As reaction temp erature is increased and norbornene concentration is decreased, productivit y increases and norbornene incorporation decreases. No more than 46 mol % n orbornene is incorporated into the copolymer using these CpA catalysts even at low feed ratios (EM greater than or equal to 0.02), and norbornene homo polymerizations with [Me2Si(Me4Cp)((NBu)-Bu-t)]TiCl2 proceed to very low co nversion (<1%). C-13 NMR spectroscopy of CpA-derived poly(ethylene-co-norbo rnene)s shows the copolymers contain virtually no consecutive norbornene se quences, and the microstructure of the resulting ethylene norbornene copoly mers is dependent on catalyst geometry.