Formation of a Constrained-Geometry Ziegler Catalyst System Containing a C1 Instead of the Usual Si1 Connection Between the Cyclopentadienyl and Amido Ligand Components
✍ Scribed by Lothar Duda; Gerhard Erker; Roland Fröhlich; Frank Zippel
- Publisher
- John Wiley and Sons
- Year
- 1998
- Tongue
- English
- Weight
- 426 KB
- Volume
- 1998
- Category
- Article
- ISSN
- 1434-1948
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✦ Synopsis
6-Amino-6-methylfulvene (4) is cleanly N-acylated by formation of [(C 5 H 4 )C(=CH 2 )NCOCMe 3 ]Zr(NEt 2 ) 2 (11) (70 % isolated), and the reaction of 8b with (Et 2 N) 2 ZrCl 2 yields treatment with pivaloylchloride/triethylamine to give the fulvene (C 5 H 4 )=C(CH 3 )NHCOCMe 3 (5c). Treatment of 4 with [(C 5 H 4 )C(=CH 2 )NSiMe 3 ]Zr(NEt 2 ) 2 (12) (76 % isolated). Treatment of complex 12 with an excess of methylalumoxane trimethylchlorosilane similarly yields the mono-N-silylated fulvene (C 5 H 4 )=C(CH 3 )NHSiMe 3 (7). Both 5c and 7 are (MAO) in toluene solution results in the generation of an active homogeneous Ziegler catalyst for the polymerization cleanly doubly deprotonated e.g. by treatment with LDA to give ligand systems [(C 5 H 4 )C(=CH 2 )NR]Li 2 [8a (R = of ethene. A comparison with the usually employed [(Me 5 C 4 )SiMe 2 NCMe 3 ]ZrCl 2 /MAO "constrained-geometry" COCMe 3 ) and 8b (R = SiMe 3 ), respectively]. Their treatment with MCl 4 • 2 THF (M = Ti, Zr) yield the spiro-metallocenes Ziegler catalyst system reveals a similar catalyst activity and performance of this novel type of a C 1 -bridged "constrained-[(C 5 H 4 )C(=CH 2 )NR] 2 M (9, 10). Complex 10a (M = Zr, R = COCMe 3 ) was characterized by X-ray diffraction. The geometry" catalyst as it is exemplified by the [(C 5 H 4 )C(= CH 2 )NSiMe 3 ]ZrX 2 (12)/MAO combination. reaction of 8a with (Et 2 N) 2 ZrCl 2 in THF gives rise to the