Ethylene polymerization catalyzed by ruthenium and iron complexes containing 2,6-bis(2-oxazolin-2-yl)pyridine (Pybox) ligand-cocatalyst system

RuX2(ethylene)(pybox) [X = Cl (1), I (2), and CF3O3 (3); pybox = 2,6-bis[(4 S)-4-isopropyl-2-oxazolin-2-yl]-pyridine] complexes have exhibited moderate catalytic activity for ethylene homopolymerization and ethylene/1-hexene c opolymerization in the presence of MAO. The incorporation of 1-hexene (27.2 mol%) in the resultant copolymer was confirmed by C-13 NMR spectrum. The r esonances corresponding to the triad sequence of HHH were negligible. A sma ll r(E).r(H) value of 0.32, where r(E) and r(H) are the monomer reactivity ratios of ethylene and 1-hexene, respectively, was thus obtained, indicatin g a significantly alternating tendency. FeCl2(pybox) (4) has also exhibited the activity for ethylene polymerization in the presence of MAO. The attem pted copolymerization of ethylene with 1-hexene by 4 gave linear polyethyle ne without incorporating 1-hexene.