This website uses cookies to give you the best user experience. If you continue
without changing your settings we'll assume you are happy to receive all RSC cookies.
You can change your cookie settings by navigating to our Privacy and Cookies page and following the instructions. These instructions
are also obtainable from the privacy link at the bottom of any RSC page.
The George and Josephine Butler Laboratory for Polymer Research, Department of Chemistry, University of Florida, Gainesville, USA
E-mail: miller@chem.ufl.edu
; Fax: +1-352-392-9741
; Tel: +1-352-392-7773
Dalton Trans., 2013,42, 9139-9147
DOI:
10.1039/C3DT50163A
Received
16 Jan 2013,
Accepted
01 Mar 2013
First published online
01 Mar 2013
Several analogues of the sterically expanded constrained geometry catalyst Me2Si(η1-C29H36)(η1-N-tBu)ZrCl2·OEt2 (2) were synthesized to assess the effect on branching and molecular weight for ethylene homopolymerization. Catalysts based on tetramethyltetrahydrobenzofluorene (TetH), ethylTetH, t-butylTetH, and octamethyloctahydrodibenzofluorenyl (OctH) bearing a diphenylsilyl bridge were prepared and characterized: Me2Si(η5-C21H22)(η1-N-tBu)ZrCl2 (3); Me2Si(η5-C23H26)(η1-N-tBu)ZrCl2 (4); and Me2Si(η5-C25H30)(η1-N-tBu)ZrCl2 (5); Me2Si(η5-C21H22)(η1-N-tBu)ZrMe2 (6); and Ph2Si(η5-C29H36)(η1-N-tBu)ZrCl2 (7). Complexes 4, 5, 6, and 7 were characterized by X-ray crystallography and displayed η5 hapticity to the carbon ring in each case, in contrast to 2. In comparison to 2, complexes 3, 4, 5, and 7 (in combination with methylaluminoxane = MAO) showed diminished branching, higher molecular weight, and higher polydispersity indices for obtained ethylene homopolymers. While 4/MAO produced the greatest molecular weight polymers, no branching was observed. Reactivity ratios were determined for the copolymerization of ethylene and 1-decene with 2/MAO. A value of rethylene = 14.9 and an exceedingly high value of r1-decene = 0.49 were found—in line with previous reports of this catalyst's unusual affinity for α-olefins.
Fetching data from CrossRef. This may take some time to load.