Sequential additions of NaOEt and benzyl chloride (BzCl) to diethyl adipate in THF afforded EtOOCCH(Bz)CH 2 CH 2 CH(Bz)COOEt (3) in high yield via successive Dieckmann condensations. This was converted to CH 2 CH 2 (2-indene) 2 (2) using standard synthetic methodology, from which 436 g of CH 2 CH 2 (2-indenyl) 2 ZrCl 2 (1) was prepared. Incorporation of a 1-alkyl substituent gave rac and meso isomers CH 2 CH 2 (1-R-2-indenyl) 2 ZrCl 2 (R ) Me, 12r, 12m; R ) Et, 14r, 14m). Methylation gave rac-and meso-CH 2 CH 2 (1-Me-2-indenyl) 2 -ZrMe 2 (15r, 15m) and CH 2 CH 2 (2-indenyl) 2 ZrMe 2 (16). CH 2 CH 2 (4-Ph-2-indene) 2 (20) was prepared similarly to 2 using 2-phenyl benzylbromide and diethyladipate/NaOEt, from which rac-and meso-CH 2 CH 2 (4-Ph-2-indenyl) 2 ZrCl 2 (19r and 19m) were prepared. Alkylation of 19m gave meso-CH 2 CH 2 (4-Ph-2-indenyl) 2 ZrMe 2 (23m). The 4-phenyl metallocenes rac-and meso-CH 2 CH 2 (1-Me-4-Ph-2-indenyl) 2 ZrCl 2 (25r and 25m) were prepared via 20. C 2 -symmetric CH 2 CH 2 (1,3-Me 2 -2-indenyl) 2 ZrCl 2 (29) was prepared to compare its polymerization behavior with 1. These zirconocenes displayed activities of up to 4320 kg PE/(g Zr‚h) for the polymerization of ethylene (9.6 bar, 80 °C, hexane) to linear PE. The activity was much lower (2-20 kg/(g Zr‚h); liquid propylene, 50 °C) for the polymerization of propylene to low molecular weight atactic polypropylene. Alkyl groups in the 1-and/or 3-positions led to a significant reduction of 2,1-insertions from 9.4% in the polymer from 1/MAO, and 9.9% from 19/MAO, to 0.1-0.4%. Attempts to prepare an isospecific catalyst were unsuccessful; substituent variation i.e., 4-phenyl in 19, did not provide effective enantiomorphic site control. Addition of H 2 has a dramatic activation effect (>100-fold) in propylene polymerization and afforded saturated propylene oligomers with activities up to 6240 kg/(g Zr‚h). The low polymer molecular weights allowed detailed NMR analysis of the end groups, which enabled the chain transfer and metallocene activation mechanisms to be identified. Copolymerization of ethylene and propylene (in liquid propylene at 50 °C with 6 mol % ethylene) afforded copolymers with activities of 1300-12500 kg/(g Zr‚h). Reactivity ratios (r E ) 41-98, r P ) 0.0025-0.0084, r E r P ) 0.1-0.7) indicate a very high preference for sequential ethylene insertions. Copolymerization of ethylene and 1-hexene (4.4 bar ethylene, heptane, 70 °C) gave copolymers with activities of up to 1100 kg/(g Zr‚h) using 12r/MAO. The copolymer microstructure showed highly preferential sequential ethylene incorporation: r E ) ca. 200, r H ) 0.004.

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 (T m2 = 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 < 10a,b < 11. Although activities 1−2 orders of magnitude lower than for 11 and 12 were found at high MAO/Zr ratios, at low cocatalyst levels activities were similar. 10a,b were also successfully activated with alternative aluminoxanes based on branched alkylaluminums (e.g. Al(CH2CHMePh)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.

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