Ethylene Polymerization by Monochloro Non-Bridged Half-Metallocene-type Zirconium Complexes Containing Phosphine Oxide-(thio)phenolate Chelating Ligands as Catalyst at High Temperature

Abstract

Ethylene polymerizations were explored by monochloro half-zirconocene complexes containing phosphine oxide-(thio) phenolate chelating ligands of the type,ClCp'Zr[X-2-R1-4-R2-6-((Ph2P=O) C6H2]2(Cp' = C5H5,a:X = O,R1= Ph,R2= H;b:X = O,R1= F,R2= H;c:X = O,R1=tBu,R2= H;d:X =O,R1= R2=tBu;e:X = O,R1= SiMe3,R2= H;f:X = S,R1= SiMe3,R2= H;Cp' = C5Me5,g:X = O,R1= SiMe3,R2= H) in the presence of Ph3CB(C6F5)4/iBu3Al as co-catalyst at high temperature(50 ~125 ℃).As reveled by the polymerization results,under optimized reaction temperature of 75 ℃,complexes a ~ d were efficient ethylene polymerization catalysts under high temperature(50 ~ 100 ℃).Catalytic activity was improved by increasing the steric bulk of R1substituent or the introduction of electron withdrawing groups at the same position.The occurrence of trimethylsilyl rendered a greatly improved temperature resistance for catalyst e than those of catalysts a ~ d,exhibiting an ethylene polymerization activity of 5628 kg /(mol Zr·h)under 100 ℃ optimized reaction temperature.The variation of coordinated atom or the substituents at the Cp moiety had certain influences upon the catalytic activity and the PDI of the resulting polymer material.