Titanium-Catalyzed Norbornene Oligomerization. Isolation of a Crystalline Heptamer with a 2,3-exo-Disyndiotactic Structure
✍ Scribed by Lido Porri; Valerio N. Scalera; Matteo Bagatti; Antonino Famulari; Stefano V. Meille
- Publisher
- John Wiley and Sons
- Year
- 2006
- Tongue
- English
- Weight
- 157 KB
- Volume
- 27
- Category
- Article
- ISSN
- 1022-1336
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✦ Synopsis
Abstract
Summary: Norbornene (NB) was oligomerized at 0 °C using AlEt~2~Cl‐TiCl~4~ at a monomer/titanium molar ratio of about 11. The oligomerization product consists of a fraction soluble in diethyl ether, amorphous by X‐ray examination, and of a crystalline fraction, insoluble in diethyl ether. The crystalline fraction was shown by powder X‐ray diffraction to consist of a NB heptamer. Single‐crystal X‐ray analysis indicated that the heptamer had a stereoregular 2,3‐exo‐disyndiotactic structure. The heptamer adopts a strained, highly irregular, folded conformation in the crystalline state. Structural differences with respect to NB oligomers obtained with zirconocene catalysts are discussed.
A view of the molecular structure of the crystalline NB heptamer.
magnified imageA view of the molecular structure of the crystalline NB heptamer.