Published in
Elsevier, Journal of Molecular Catalysis A: Chemical, 1-2(264), p. 260-269
DOI: 10.1016/j.molcata.2006.09.011
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Synthesis and catalytic applications of C1 symmetric group 4 ansa-metallocene complexes
,
Sanjiv Prashar,
Luis F. Sánchez-Barba ,
Dorian Polo-Cerón,
Mariano Fajardo,
Antonio Antiñolo,
Antonio Otero,
Miguel A. Maestro,
César J. Pastor
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Abstract
The group 4 ansa-metallocene complexes with chiral substituent bearing cyclopentadienyl ligands, [M{Me2Si(η5-C5Me4)(η5-C5H3{CHRR′})}Cl2] (R=Pri, R′=Me (9); R=Pri, R′=Ph (10); R=But, R′=Me (11); R=But, R′=Ph (12); M=Zr (a), Hf (b)), were synthesized by the reaction of the dilithium compounds, Li2{Me2Si(C5Me4)(C5H3{CHRR′})} (R=Pri, R′=Me (5); R=Pri, R′=Ph (6); R=But, R′=Me (7); R=But, R′=Ph (8)), with the tetrachloride salts of the transition metal. The molecular structures of 11a and 12a have been determined by single-crystal X-ray diffraction studies. The catalytic behaviour of 9–12 in the polymerization of ethylene and propylene has been studied. Isotactic polypropylene with [mmmm] pentads of the order of 60% were obtained with the C1 symmetric ansa-zirconocene catalysts.