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Ethylene polymerization with long‐lifetime monopendant thienyl‐substituted group 4 metallocenes
Author(s) -
Li Aike,
Xiao Wei,
Ma Haiyan,
Huang Jiling
Publication year - 2014
Publication title -
applied organometallic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.53
H-Index - 71
eISSN - 1099-0739
pISSN - 0268-2605
DOI - 10.1002/aoc.3153
Subject(s) - methylaluminoxane , chemistry , cyclopentadienyl complex , ethylene , thiophene , metallocene , polymerization , polyethylene , catalysis , polymer chemistry , intramolecular force , crystal structure , monomer , crystallography , medicinal chemistry , stereochemistry , organic chemistry , polymer
A series of group 4 metallocenes (RCp)[Cp―(bridge)―(2‐C 4 H 3 S)]MCl 2 [M = Ti ( C1 , C2 , C3 , C4 ); M = Zr ( C5 , C6 , C7 , C8 )] bearing a pendant thiophene group on a cyclopentadienyl ring have been synthesized, characterized and tested as catalyst precursors for ethylene polymerization . The molecular structures of representative titanocenes C2 and C4 were confirmed by single‐crystal X‐ray diffraction and revealed that both complexes exist in an expected coordination environment for a monomeric bent metallocene. No intramolecular coordination between the thiophene group and the titanium center could be observed in the solid state. Upon activation by methylaluminoxane (MAO), titanocenes C1 , C2 , C3 , C4 showed moderate catalytic activities and produced high‐ or ultra‐high‐molecular‐weight polyethylene ( M v 70.5–227.1 × 10 4 g mol −1 ). Titanocene C3 is more active and long‐lived, with a lifetime of nearly 9 h at 30 °C. At elevated temperatures of 80–110 °C, zirconocenes C5 , C6 , C7 , C8 displayed high catalytic activities (up to 27.6 × 10 5 g PE (mol Zr) −1 h −1 ), giving high‐molecular‐weight polyethylene ( M v 11.2–53.7 × 10 4 g mol −1 ). Even at 80 °C, a long lifetime of at least 2 h was observed for the C8/MAO catalyst system. Copyright © 2014 John Wiley & Sons, Ltd.