Ethylene, a-olefin and norbornene copolymerization with the stereorigid catalyst systems iPr[FluCp]ZrC12/MAO and Me2Si[Ind]2ZrCl2/MAO b, SUMMARY:The stereorigid ansa-metallocene catalysts [2,4-cyclopentadien-1-ylidene(isopropylidene)fluoren-9-ylidene]zirconium dichloride/methylaluminoxane (iPr[FIuCp]ZrCl,/MAO) and [(dimethylsilylene)bis(~5-inden-1-ylidene)]zirconium dichloride/methylaluminoxane (Me,Si[Ind],-ZrCl,/MAO) are different in respect to the symmetry and, therefore, to the behaviour of the stereospecifity, in the size of the angle between the planes of the n-ligand systems and in the homopolymerization behaviour of ethylene and propene. The present paper concerns itself with comparing the investigations of the ethylene/a-olefin and the ethylenekycloolefin copolymerization with both catalyst systems. The main kinetic result for both catalysts is that the a-olefins show an accelerating effect on the ethylene polymerization rate during the copolymerization whereas norbornene shows exclusively a rate-decreasing effect. The acceleration effect can be explained by an increase in the concentration of active centres and/or an increase of the rate constant of the ethylene insertion. The analysis of the microstructures of the formed copolymers by the use of statistical models demonstrates that in copolymers with a high content of a-olefins, the experimental trial distributions can only be described satisfactorily with second-order Markovian statistics. That means that in this case the last two monomers have influence on the insertion of the subsequent monomer. A further main result of all investigated copolymerizations is that the r-parameters for the a-olefin insertion are more favourable for the system iPr[FluCp]ZrCl,/ MA0 than for the system Me,Si[Ind]2ZrCI,/MAO; the reason for this is the different size in the coordination gap aperture of the n-ligands. Furthermore, the r-parameters show only a small dependence on the chain length of the a-olefin. Finally, it is remarkable that the stereospecifity (syndiotactic or isotactic a-olefin blocks) remains intact in the copolymers. 0 1993, Hiithig & Wepf Verlag, Base1CCC 0025-1 16X/93/$05.00

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Die Polymerisationen wurden bei 25 "C, einem Propendruck von 2 bar und einem Al/Zr-Verhlltnis von 1 280 : 1 durchgefiihrt. Die Metallocen-Lijsung wurde 20 Minuten lang mit 2 mL einer 1 lproz. Ixisung von MA0 in Toluol voraktiviert und dann mit einer a) Teil4 G. Fink, D. Schnell, Angew. Makromol. Chem. 105, 39 (1982). 0 1992, Hiithig & Wepf Verlag, Base1 CCC 0025-1 16)

The ethylene and propene homopolymerization was investigated by means of the C,-symmetric [2,4-cyclopentadien-1-ylidene(isopropylidene)fluoren-9-ylidene]zirconium dichloride/ methylaluminoxane (iPr[FluCp]ZrCl,/MAO) and the C,-symmetric [(dimethylsilylene)bis(q5inden-1-ylidene)]zirconium dichloride/methylaluminoxane (Me,Si[Ind]2ZrC12/MAO) catalyst systems in toluene. Surprisingly, the C,-symmetric catalyst polymerizes propene faster than ethylene. The main results of the kinetic analysis are a first-order dependence on the concentration of Zr but a bell-shape in the plot of the polymerization rate versus log([Al] : [Zr]). This is true for both catalyst systems. Furthermore with increasing [All : [Zr] ratio the fraction of rmrr pentads is decreased continuously with the C,-symmetric catalyst; in the same direction the molecular weights are decreased. On the contrary with the C,-symmetric catalyst the stereospecificity and the molecular weights remain constant. The kinetic results reflect the complex role of the MAO, i. e. the existence of sterically more and more tight contact species between metallocene and MA0 components with increasing [All : [Zr] ratio. The different behaviour of the two catalyst systems concerning stereospecificity and molecular weights of the polymers are due to different symmetry and different size of the angle between the planes of the n-ligand systems. Chirale ansa-lirconocen-Komplexe in Kombination rnit Methylaluminoxan (MAO) erfahren in jungerer &it ein enormes Interesse bezuglich des Ablaufs der stereospezifischen Polymerisation mit loslichen Ziegler-Katalysatoren. Bei den Versuchen einer mechanistischen Interpretation wird aber meist die Metallocen-Komponente zu sehr allein betrachtet und das Zusammenspiel rnit der MAO-Komponente zu wenig berucksichtigt, bzw. die Kinetik dieser Systeme nicht analysiert. In der vorliegenden Arbeit wurden die Ethylen-und Propenhomopolymerisation rnit den MAO-aktivierten Katalysatorsystemen [2,4-Cyclopentadien-l-yliden(isopropyliden)fluoren-9-yliden]zirconiumdichlorid (iPr [FluCplZrCl,) ' -3) und [(Dimethylsilylen)bis(~5-inden-l-yliden)]zirconiumdichlorid (Me,Si[Ind],ZrC1,)4-6) in Toluol bei 25 "C mit Hilfe kinetischer und produktanalytischer Methoden unter Variation der Parameter Metallocen-, MAO-und Monomerkonzentration untersucht. Die genauen Polymerisationsbedingungen sind im Experimentellen Teil beschrieben. a) Part 5 : N. Herfert, G. Fink, Makromol. Chem. 193, 773 (1992). b, iPr[FluCp]ZrC12 = [2,4-Cyclopentadien-l-yliden(isopropyliden)fluoren-9-yliden]zirconiumdichlorid. MA0 = Methylaluminoxan. Me,Si[Ind],ZrCI, = [(Dimethylsilylen)bis(q5-inden-1 -yliden)]zirconiumdichlorid. 0 1992, Hiithig & Wepf Verlag, Basel CCC 0025-1 16)

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