Syntheasis and evaluation of zirconocene cataysts for olefin polymerization

Abstract

The reaction of 1-indanone with 4-tolylmagnesium bromide and subsequent dehydration of an intermediate alcohol gave 1-tolylindene (1) ligand. The reaction of 1 with n-butyllithium gave 1-tolylindenyl lithium, which was then treated with $ZrCl_4$ (0.5 equiv.) to produce a mixture of two isomers of bis (1-tolylindenyl)zirconium dichloride (2a, 2b). The mixture (2a, 2b) were separated by fractional recrystallization in dichloromethane followed by repeated extraction with toluene. Treatment of 2a and 2b with methyllithium (2 equiv.) afforded the respective dimethylated complex 3a and 3b. Complex 3a with only one $^1H$-NMR methyl resonance shows it to be a racemic-like isomer whereas two methyl reasonances for 3b to be a meso-like isomer. In addition the ansa-isopropyl (cyclopentadienyl)(1-tolylindenyl) zirconium dichloride (5) was prepared by treatment of $ZrCl_4$ with the dilithium salt of