Ethylene polymerization catalyzed by Pd-based β-ketoiminato complexes/MAO systems

The substituted β-ketoiminato palladium(II) complexes, Pd[CH3C(O)CHC(NAr)CH3](Pph3)(Me) (1 Ar = α-napthyl, 2 Ar = fluorenyl), can be prepared from the reaction of (COD)PdMeCl and Pph3 with the appropriate ligand. After activation of 1 and 2 with methylaluminoxane (MAO), the resulting palladium(II) complexes are used as catalysts for ethylene polymerization, yielding linear polyethylene. The effects of temperature, co-catalyst to catalyst molar ratio and polymerization time on catalyst activities are reported. The catalyst activity decreases above −20 °C due to catalyst deactivation and optimum co-catalyst to catalyst ratio is 300:1.