Cationic metallocene/borate catalysts, generated from zirconocene dimethyl compounds, L n ZrMe2, and anilinium borate, [HNMe2Ph]+[B(C6F5)4]-, were used to polymerize 5-amino-1-pentenes and one 4-amino-1-butene with dimethyl, diethyl, diisopropyl, or diphenyl substitution patterns on nitrogen. The monomer 5-(N,N-diisopropylamino)-1-pentene showed the highest activity with Cp*2ZrMe2/borate and was used for all further investigations. The catalytic system Cp*2ZrMe2/borate was 4 times more active than the corresponding methylaluminoxane-based system and 180 times more active than the heterogeneous system, TiCl3/Al(i-Bu)3. 1-Hexene and 5-(N,N-diisopropylamino)-1-pentene were polymerized with Cp*2ZrMe2 and rac-ethylenebis(tetrahydroindenyl) zirconium dimethyl, rac-EB(THI)ZrMe2. Polymerization of both monomers with Cp*2ZrMe2 displayed similar activities. Hexene polymerizations with rac-EB(THI)ZrMe2 were 30 times more active than those with aminopentene. 5-(N,N-Diisopropylamino)-1-pentene polymerizations gave rise to isotactic poly(aminopentene) with C 2 symmetric catalysts, syndiotactic polymer with a C s symmetric catalyst, and atactic polymer with achiral catalyst precursors.

Metallocene/borate catalysts, generated from zirconocene dimethyl compounds, L n ZrMe2, and anilinium borate, [HNMe2Ph]+[B(C6F5)4]-, were used to copolymerize 5-N,N-diisopropylamino-1-pentene with 1-hexene and 4-methyl-1-pentene. The selected zirconocenes, bis(pentamethylcyclopentadienyl)zirconium(IV) dimethyl (Cp*2ZrMe2) and rac-ethylenebis(4,5,6,7-tetrahydroindenyl)zirconium(IV) dimethyl (rac-EB(THI)ZrMe2), provided atactic and isotactic materials, respectively. The isotactic polymers produced were amorphous or crystalline depending of the monomer. The calculated reactivity ratios for the copolymerization of 5-N,N-diisopropylamino-1-pentene with 1-hexene and metallocene rac-EB(THI)ZrMe2 indicate that this system approximates an ideal azeotropic copolymerization with r 1 = 1.11 and r 2 = 0.87. Estimates for the reactivity ratios for the copolymerization of 5-N,N-diisopropylamino-1-pentene with 4-methyl-1-pentene were r 1 = 3 and r 2 = 1 for rac-EB(THI)ZrMe2 and r 1 = 5 and r 2 = 0.5 for Cp*2ZrMe2. The polymerization of 1-hexene in the presence of the saturated 1-N,N-diisopropylaminopentane with rac-EB(THI)ZrMe2/borate was compared with analogous copolymerizations of 1-hexene/5-N,N-diisopropylamino-1-pentene. The aminopentene was more effective than the aminopentane in inhibiting the rate of total monomer conversion, implicating both intra- and intermolecular mechanisms for inhibition by the amine. Copolymers of 4-methyl-1-pentene/5-N,N-diisopropylamino-1-pentene produced with rac-ethylenebisindenyl zirconium(IV) dimethyl (rac-EBIZrMe2)/borate have higher decomposition temperatures with increasing amounts of aminopentene. This copolymer can be protonated with HCl to yield a methanol-soluble material.

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Forty years after Natta's discoveries of stereospecific olefin polymerization with Ziegler catalysts, new catalysts are causing a renaissance in stereospecific olefin polymerization. Metallocene Ziegler‐Natta catalysts are unprecedented in their ability to polymerize α‐olefins to a variety of polymer microstructures.1 Isotactic, syndiotactic, atactic and stereoblock poly(α‐olefins) have been produced using catalysts derived from group 4 metallocene catalyst precursors.

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