566149-90-4Relevant academic research and scientific papers
Ansa-zirconocenes based on N-substituted 2-methylcyclopenta[b]indoles: Synthesis and catalyst evaluation in liquid propylene polymerization
Van Baar, Jan F.,Horton, Andrew D.,De Kloe, Kees P.,Kragtwijk, Eric,Mkoyan, Shaen G.,Nifant'ev, Ilya E.,Schut, Peter A.,Taidakov, Ilya V.
, p. 2711 - 2722 (2003)
Cyclopenta[b]indole-based ansa-zirconocenes were prepared and studied as catalysts for propylene polymerization. Substituted 2-methyl-4-R-1,4-dihydrocyclopenta[b]indoles (R = Ph, 7a; R = o-Tol, 7b; R = Me, 7c) were synthesized and converted into the racemic forms of the corresponding ansa-zirconocenes Me2Si(2-Me-4-R-cyclopenta[b]indolyl)2ZrCl2 (R = Ph, 10a; R = o-Tol, 10b; R = Me, 10c). The structure of 10a was determined by X-ray analysis. The effectiveness in polymerization catalysis of the metallocenes compared to benchmark metallocenes rac-Me2Si(2-Me-4-Ph-Ind)2ZrCl2 (11) and rac-Me2Si(2-Me-4,5-BzInd)2ZrCl2 (12) was investigated in liquid propylene at 70°C. Both 10a and 10b with MAO cocatalyst afforded highly isospecific (mmmm 95.9, 95.6%, respectively) and highly regisospecific polypropylene (0.17, 0.34% imbedded regioerrors), which exhibited a high melting point (Tm2 = 154.2, 156.3°C). The polymer properties were intermediate between those of 11 and 12, with the molecular weight, stereospecificity, and melting point increasing in the order 12 2CHMePh)3, obtained from α-methylstyrene), with measured activities up to 16.6 TON/((g of Zr) h) (10a/AKO). Surprisingly, no consistent effect on polymer properties of varying either the 4-aryl substituent of the cyclopenta[b]indole group or the cocatalyst was found.
