J. Klosin et al., Heteroatom-substituted constrained-geometry complexes. Dramatic substituent effect on catalyst efficiency and polymer molecular weight, ORGANOMETAL, 20(13), 2001, pp. 2663-2665
The new constrained-geometry complexes (CGC) [(eta (5)-C9H5X)(SiMe2-t-BU)Ti
R2 (X = 2-OEt (1a,b), 2-NMe2 (2a,b), 3-OMe (3a,b), 3-NC4H4 (4a,b); R = Cl,
Me) have been synthesized with alkoxy and amino substituents attached to a
second and third indenyl position. Four of the new complexes (1a-4a) have b
een characterized by single-crystal X-ray analysis. An ethylene-octene copo
lymerization study revealed an enormous substituent effect, both on the cat
alysts' activity and the molecular weight of produced polymers. The 3-amino
-substituted complex 4b exhibits the highest catalytic activity and forms t
he highest molecular weight ethylene/octene copolymers that have ever been
reported for this class of catalysts.