ansa-Metallocene (R-Ph)2C(Cp)(Ind)MCl2 with electron withdrawing substituents on phenyl groups for olefin polymerization

The new ansa-complexes (R-Ph)2C(Cp)(Ind)MCl2 (R = CF3, F, Cl; M = Ti, Zr or Hf) were synthesized from the reaction of dilithium salt of the corresponding ligands with appropriate group 4 metal halides. They were tested for ethylene homopolymerization and copolymerization in the presence of methylaluminoxane (MAO) at various ethylene pressures and temperatures. In the case of zirconocenes, complexes 2 (R = CF3) and 8 (R = Cl) demonstrated much higher catalytic activity than complexes 10 (Ph2C(Cp)(Ind)ZrCl2) and 5 (R = F) in ethylene polymerization. The same trend was observed in titanocenes and hafnocenes. The electronic and geometric effects of substituents at the phenyl group on the polymerization activity were easily noticed. For the ethylene/1-hexene or 1-octene copolymerization, 2 also showed the highest catalytic activity, and the copolymers from complex 8 possessed the highest 1-hexene and 1-octene contents.

Graphical abstractThe new ansa-complexes (R-Ph)2C(Cp)(Ind)MCl2 (R = CF3, F, Cl; M = Ti, Zr or Hf) were used on ethylene homopolymerization and ethylene/α-olefin copolymerization. Zirconocenes contained CF3 or Cl showed the highest catalytic activity. The copolymer from zirconocene contained Cl possessed the highest α-olefin contents.Figure optionsDownload full-size imageDownload as PowerPoint slide