Synthesis, characterization and application of benzyl-substituted cyclopentadienyl lanthanide complexes as catalyst precursors for the syndiotactic polymerization of methyl methacrylate

Benzyl-substituted cyclopentadienyl lanthanide complexes were synthesized and characterized by elemental analysis, MS and IR spectroscopy. The analytical data point out the formation of monomeric. unsolvated complexes. In conjunction with AI(Et)₃ as co-catalyst. the title complexes are efficient catalysts for the syndiotactic polymerization of methyl methacrylate. For the complex (C₆H₅CH₂C₅H₄)₂YCl, under the optimum polymerization conditions (60 °C, n(MMA) : n(catalyst) : n(co-catalyst)=1000 : 1 : 10), a predominantly syndiotactic (rr=66%) polymer of high molecular weight (M_n= 105000) was obtained.