| Abstract
| - Chemoselective elimination of Me3SiCl from mixed silyl cyclopentadienes cleanly affords 2 and 7. Reaction of the precursor catalysts with (aminomethyl)polystyrene (AMPS) leads to the assembly of constrained-geometry catalysts (CGCs) 8 and 9. These novel assembled catalyst systems in conjunction with MAO were found to be active for ethylene and ethylene/1-octene polymerization.
- The reaction of TiCl4 with (chlorodimethylsilyl)(trimethylsilyl)cyclopentadiene results inthe chemoselective elimination of Me3SiCl and cleanly affords ((chlorodimethylsilyl)cyclopentadienyl)titanium trichloride (2). Likewise, the reaction of TiCl4 with (chlorodimethylsilyl)(trimethylsilyl)tetramethylcyclopentadiene (6) also results in the chemoselectiveelimination of Me3SiCl and cleanly affords ((chlorodimethylsilyl)tetramethylcyclopentadienyl)titanium trichloride (7). This observation is in sharp contrast to the reaction of 6 with ZrCl4,which results in the chemoselective elimination of Me3SiCl but affords a mixture of half-sandwich and zirconocene complexes. Support of complex 2 or 7 on (aminomethyl)polystyrene(AMPS, 1% cross-linking, 1.3 wt % N, 0.928 mmol of N/g of support), where the mole ratioof amine content of the support to precursor catalysts was selected to be 3:1, leads to theassembly of the constrained-geometry catalyst (CGCs) 8 or 9, respectively. From the 29SiNMR, the presence of a single silicon species was observed in complex 9, which has beenattributed to the CGC form. However, for 8 two silicon resonances were observed, one ofwhich has been attributed to the CGC form and the other to a titanium amide moiety. TheTi:Si:Cl ratio for both 8 and 9 was found to be 1:1:4 through elemental analyses. Complexes8 and 9, in conjunction with MAO as the cocatalyst, were tested for ethylene homopolymerization and ethylene/1-octene copolymerization. The thermal properties and the molecularweights of the resulting polymers were determined. The observation of ethylene-co-1-octeneprovides independent evidence for the formation of supported CGC from the syntheticprotocol.
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