Titanium‐Catalyzed Norbornene Oligomerization. Isolation of a Crystalline Heptamer with a 2,3‐exo‐Disyndiotactic Structure期刊界 All Journals 搜尽天下杂志传播学术成果专业期刊搜索期刊信息化学术搜索

按检索

Titanium‐Catalyzed Norbornene Oligomerization. Isolation of a Crystalline Heptamer with a 2,3‐exo‐Disyndiotactic Structure

Authors:	Lido Porri Valerio N Scalera Matteo Bagatti Antonino Famulari Stefano V Meille

Abstract:	Summary: Norbornene (NB) was oligomerized at 0 °C using AlEt₂Cl‐TiCl₄ 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.

Keywords:	catalysts crystal structures polynorbornene stereoregular oligomerization titanium catalysts zirconocene catalysts