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Symmetrical and lopsided zirconocene pro‐catalysts
Author(s) -
Ewen John A.
Publication year - 1995
Publication title -
macromolecular symposia
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.257
H-Index - 76
eISSN - 1521-3900
pISSN - 1022-1360
DOI - 10.1002/masy.19950890119
Subject(s) - catalysis , materials science , composite material , chemistry , organic chemistry
Me 2 C[1‐Cp‐9‐Flu]ZrCl 2 derivatives with H‐, CH 3 ‐and (CH 3 ) 3 C‐ substituents β to the Cp bridgehead carbon atom as well as complexes having mono‐ or di‐substituted fluorenyl ligands (R = CH 3 ‐, (CH 3 ) 3 C‐, CH 3 O‐, CH 3 OCH 2 ‐, (CH 3 ) 3 CC≡C‐, (CH 3 ) 2 N‐, F‐, and Cl‐) have been investigated as propylene polymerization pro‐catalysts. Steric effects from the β‐Cp substituents determine the iso‐, hemi‐iso‐, and syndio‐specificities of the catalysts. The relative stereospecificities of Me 2 Si[1‐Cp‐3 t‐Bu ‐9‐Flu]ZrCl 2 and rac ‐Me 2 Si[1‐Ind‐3‐ t ‐Bu] 2 ZrCl 2 are in accord with molecular models. The more un‐symmetrical the catalysts are the more m and mm stereosequences there are in s‐PP. The m dyads also increase with the concentration of Me 2 C[1‐Cp‐9‐Flu‐2‐OMe]ZrCl 2 .