Synthesis and reactivity of (C6F5)3B-N-heterocycle complexes, 2a -: (C6F5)3B-indole complexes as metallocene activators in ethylene polymerization and ethylene-propylene copolymerization

The reaction of pyrroles and indoles with perfluoroarylboranes produces 1:1 B-N complexes that contain highly acidic sp(3) methylenses. these complexes are stable and can be used as a proton source for the generation of methyl-metallocene cations. Indole is preferred over pyrrole. the 1:1:1 borane:indole:dimethylmetallocene compositions are, in some instances, more active than the 500:1 MAO:metallocene catalysts. In addition, the Ind(2)ZrMe(2)/Indole-B(C6F5)(3) and related catalyst systems require a lower amount of AIR(3) scavenger and are more stable compared to the Ind(2)ZrMe(2)/B(C6F5)(3) catalyst. Also, Ind(2)ZrCl(2)/Al(i-Bu)(3)/indole-B(C6F5)(3) is an active catalyst system. In ethylene/propylene solution copolymerization catalyzed by Ind(2)ZrMe(2), the most active catalysts are indole-B(C6F5) and 5-benzyloxy-indole-B-(C6F5)(3).