Ethylene homopolymerization and ethylene/1-hexene copolymerization catalysed by mixed salicylaldiminato cyclopentadienyl zirconium complexes

Three new mixed salicylaldiminato cyclopentadienyl zirconium complexes Cp′[2-Bu^t-6-(C₆H₁₁NCH)C₆H₃O]ZrCl₂ (Cp′ = ⁿBuC₅H₄ (3a), ^tBuC₅H₄ (3b) and Me₄C₅H (3c)) were prepared and the structure of complex 3c was confirmed by X-ray diffraction analysis. All of the three complexes showed high activities for ethylene homopolymerization with the activation of methylaluminoxane, and 3a showed the highest activity up to 1.15 × 10⁶ g PE/mol Zr h for ethylene homopolymerization at 70 °C. The ¹³C NMR spectrum showed that the obtained polymer is linear polyethylene. Complexes 3a-c also catalysed ethylene/1-hexene copolymerization with high activities from 6.29 × 10⁵ to 12.3 × 10⁵ g Copolymer/mol Zr h and with 0.89-1.39% 1-hexene incorporation level. In addition, the influence of the substituted alkyl on Cp on the catalytic behavior of corresponding zirconium complexes was discussed.