The polymerization of the substituted olefins 4-methylpentene and vinylcyclohexane by dibenzyl titanium and zirconium complexes of three amine bis(phenolate) ligands is reported. The ligands featured a dimethylamino side-arm donor and either electron-withdrawing (Cl and Br) or methyl phenolate substituents. After activation with B(C6F5)(3), the zirconium catalysts exhibited a higher activity than the titanium catalysts toward these bulky olefins. Very high weight-average molecular weight poly(4-methylpentene) was obtained with the zirconium catalysts. The zirconium catalysts were employed in 1-hexene polymerization, and their activity was found to be the highest ever reported for catalysts of the amine bis(phenolate) family. The catalysts featuring methyl phenolate substituents showed a higher activity toward these substituted olefins than the electron-poor catalysts; this trend was opposite to their activity toward 1-hexene. (c) 2005 Wiley Periodicals, Inc.