Ethylene Homopolymerization and Copolymerization with Functionalized 5-Norbornen-2-yl Monomers by a Novel Nickel Catalyst System

The homopolymerization and the copolymerization of ethylene with functionalized 5-norbornen-2-yl derivatives by the nickel catalyst system L( i Pr 2 )Ni(η 1 -CH 2 Ph)(PMe 3 ) ( 1 ) [L = N -(2,6-diisopropylphenyl)-2-(2,6-diisopropylphenylimino)propanamide] and Ni(COD) 2 (bis(1,5-cyclooctadiene)nickel) produces polymers with high molecular weights and narrow molecular weight distributions. A typical ethylene polymerization reaction proceeds under 100 psi of ethylene and at 20 °C, using 1 (0.34 mM) and Ni(COD) 2 (0.83 mM). Likewise, under similar conditions, the copolymerization of ethylene with 5-norbornen-2-yl acetate ( 3 ) (0.15 M) for 90 min by 1 (0.67 mM) and Ni(COD) 2 (1.67 mM) produced a high molecular weight functionalized polyethylene bearing ester functionalities. 5-Norbornen-2-ol (0.15 M) underwent a similar copolymerization with ethylene for 20 min to yield a hydroxy-functionalized polyethylene. Narrow molecular weight distributions, coupled with the increase of polymer molar mass with time, are consistent with a quasi-living polymerization process in the case of ethylene homopolymerization and ethylene copolymerization with 3 .