Synthesis of monoalkoxy- and trialkoxy-substituted half-sandwich titanium complexes PhCH2CpTiCl3-n (OR)n (n = 1 or 3) as catalysts for syndiotactic styrene polymerization
✍ Scribed by Hao Zhang; Qihui Chen; Yanlong Qian; Jiling Huang
- Publisher
- John Wiley and Sons
- Year
- 2005
- Tongue
- English
- Weight
- 167 KB
- Volume
- 19
- Category
- Article
- ISSN
- 0268-2605
- DOI
- 10.1002/aoc.834
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✦ Synopsis
Two new series of various substituted half-sandwich titanium complexes PhCH 2 CpTiCl 2 (OR) (R = Et (1), i Pr (2), t Bu (3), cyclohexyl (4), benzyl (5)) and PhCH 2 CpTi(OR) 3 (R = Et (6), i Pr (7), t Bu (8), cyclohexyl (9), benzyl (10)) were prepared from PhCH 2 CpTiCl 3 with lithium alkoxide or alcohol in the presence of triethylamine. All complexes were well characterized by 1 H NMR, MS, infrared spectroscopy and elemental analysis or high-resolution MS. Complexes 1-5 have two conformations, which were confirmed by temperature-dependent NMR. All complexes were tested as catalyst precursors for the syndiotactic polymerization of styrene. The syndiotactic polystyrene obtained exhibits low molecular weight (M w = 2.78 × 10 4 ) and narrow molecular weight distribution (M w /M n = 1.50). The different alkoxy ligands affected the activities slightly. The existence of the additional phenyl group on the cyclopentadienyl ligand stabilized the active species more effectively, which was reflected by the activities and syndiotacticities of all complexes, and even at high temperature the activities still kept high. The effects of Al/Ti and time on the syndiotactic styrene polymerization by complex 1 were investigated.