Zirconium bis-indenyl compounds. The influence of substituents on the ethene polymerization behavior of 1- and 2-substituted (R-Ind)2ZrCl2/MAO catalysts

A series of [1-R-Ind]2ZrCl2 (R=H, Me, Et, iPr, tBu, SiMe3, Bz, Ph, 1-Naph) and [2-R-Ind]2ZrCl2 (R=Me, Et, SiMe3, Bz, Ph) metallocenes were used in MAO co-catalyzed ethene polymerization reactions. The sizes of the ligands were measured from the perspective of the metal using the Tolman cone angle (θ), numerical solid angle and analytical solid angle measurement methods. Steric arguments permit an explanation of the polymerization activity between the different catalysts. The 1-substituted catalysts, in general were more active than their 2-substituted analogs, the difference becoming greater as the size of the R-group increased.