Abstract
This paper reports the convenient "one-pot" synthesis of a bifunctional -Me4Cp̂ phenolate- ligand and the efficient "one-step" synthesis of the corresponding TiIV and ZrIV complexes. The reaction of 2-bromo-4-methylphenol with 2 equiv of nBuLi followed by addition of 2,3,4,5-tetramethyl-2-cyclopentenone produces the bifunctional mono-Cp phenol ligand precursor 2-(tetramethylcyclopentadienyl)-4-methylphenol ((TCP)H2, 1). Reaction of 1 with Ti(CH2-Ph)4 at 60°C in toluene cleanly generates (TCP)Ti(CH2Ph)2 (2), while the corresponding reaction with Zr(CH2Ph)4 at higher temperatures affords the chelated C2-symmetric zirconocene (TCP)2Zr (3). In solution at room temperature, the two benzyl groups of 2 are magnetically equivalent, however, in the solid state, X-ray diffraction reveals that one benzyl group is coordinated in a normal η1-fashion and the other in an η2-mode. The small Cp-(centroid)-Ti-O angle of 107.7(2)° in 2 indicates sterically open features in common with amido-based "constrained geometry" polymerization catalysts. Low-temperature NMR-scale reactions of 2 with B(C6F5)3 and Ph3C+B(C6F5)4- indicate the formation of the corresponding cationic complexes (TCP)TiCH2Ph+ PhCH2B(C6F5)3- (4) and (TCP)TiCH2Ph+B(C6F5) 4- (5). Upon activation with Ph3C+B(C6F5)4 -, complex 2 is highly active for ethylene, propylene, and styrene polymerization.
| Original language | English |
|---|---|
| Pages (from-to) | 5958-5963 |
| Number of pages | 6 |
| Journal | Organometallics |
| Volume | 16 |
| Issue number | 26 |
| Publication status | Published - Dec 23 1997 |
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ASJC Scopus subject areas
- Inorganic Chemistry
- Organic Chemistry
Cite this
A novel phenolate "constrained geometry" catalyst system. Efficient synthesis, structural characterization, and α-olefin polymerization catalysis. / Chen, You Xian; Fu, Peng Fei; Stern, Charlotte L.; Marks, Tobin J.
In: Organometallics, Vol. 16, No. 26, 23.12.1997, p. 5958-5963.Research output: Contribution to journal › Article
}
TY - JOUR
T1 - A novel phenolate "constrained geometry" catalyst system. Efficient synthesis, structural characterization, and α-olefin polymerization catalysis
AU - Chen, You Xian
AU - Fu, Peng Fei
AU - Stern, Charlotte L.
AU - Marks, Tobin J
PY - 1997/12/23
Y1 - 1997/12/23
N2 - This paper reports the convenient "one-pot" synthesis of a bifunctional -Me4Cp̂ phenolate- ligand and the efficient "one-step" synthesis of the corresponding TiIV and ZrIV complexes. The reaction of 2-bromo-4-methylphenol with 2 equiv of nBuLi followed by addition of 2,3,4,5-tetramethyl-2-cyclopentenone produces the bifunctional mono-Cp phenol ligand precursor 2-(tetramethylcyclopentadienyl)-4-methylphenol ((TCP)H2, 1). Reaction of 1 with Ti(CH2-Ph)4 at 60°C in toluene cleanly generates (TCP)Ti(CH2Ph)2 (2), while the corresponding reaction with Zr(CH2Ph)4 at higher temperatures affords the chelated C2-symmetric zirconocene (TCP)2Zr (3). In solution at room temperature, the two benzyl groups of 2 are magnetically equivalent, however, in the solid state, X-ray diffraction reveals that one benzyl group is coordinated in a normal η1-fashion and the other in an η2-mode. The small Cp-(centroid)-Ti-O angle of 107.7(2)° in 2 indicates sterically open features in common with amido-based "constrained geometry" polymerization catalysts. Low-temperature NMR-scale reactions of 2 with B(C6F5)3 and Ph3C+B(C6F5)4- indicate the formation of the corresponding cationic complexes (TCP)TiCH2Ph+ PhCH2B(C6F5)3- (4) and (TCP)TiCH2Ph+B(C6F5) 4- (5). Upon activation with Ph3C+B(C6F5)4 -, complex 2 is highly active for ethylene, propylene, and styrene polymerization.
AB - This paper reports the convenient "one-pot" synthesis of a bifunctional -Me4Cp̂ phenolate- ligand and the efficient "one-step" synthesis of the corresponding TiIV and ZrIV complexes. The reaction of 2-bromo-4-methylphenol with 2 equiv of nBuLi followed by addition of 2,3,4,5-tetramethyl-2-cyclopentenone produces the bifunctional mono-Cp phenol ligand precursor 2-(tetramethylcyclopentadienyl)-4-methylphenol ((TCP)H2, 1). Reaction of 1 with Ti(CH2-Ph)4 at 60°C in toluene cleanly generates (TCP)Ti(CH2Ph)2 (2), while the corresponding reaction with Zr(CH2Ph)4 at higher temperatures affords the chelated C2-symmetric zirconocene (TCP)2Zr (3). In solution at room temperature, the two benzyl groups of 2 are magnetically equivalent, however, in the solid state, X-ray diffraction reveals that one benzyl group is coordinated in a normal η1-fashion and the other in an η2-mode. The small Cp-(centroid)-Ti-O angle of 107.7(2)° in 2 indicates sterically open features in common with amido-based "constrained geometry" polymerization catalysts. Low-temperature NMR-scale reactions of 2 with B(C6F5)3 and Ph3C+B(C6F5)4- indicate the formation of the corresponding cationic complexes (TCP)TiCH2Ph+ PhCH2B(C6F5)3- (4) and (TCP)TiCH2Ph+B(C6F5) 4- (5). Upon activation with Ph3C+B(C6F5)4 -, complex 2 is highly active for ethylene, propylene, and styrene polymerization.
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M3 - Article
VL - 16
SP - 5958
EP - 5963
JO - Organometallics
JF - Organometallics
SN - 0276-7333
IS - 26
ER -