Heterogeneous Constrained-Geometry Zirconium Catalysts

Heterogeneous constrained-geometry catalysts were prepared by immobilizing Zr(NMe 2 ) 4 on a heterogenized ansa -cyclopentadienylamino ligand of type (RN)R‘R‘ ‘Si(C 5 R‘ ‘‘ 4 ): surface 1, R = −O-Me 2 Si(CH 2 ) 3; R‘, R‘ ‘, R‘ ‘‘ = Me; surface 2, R = −O-Me 2 Si(CH 2 ) 3; R‘, R‘ ‘‘ = Me, R‘ ‘= H. The preparation of the constrained-geometry catalyst ligand on a silica surface has been carried out in two steps: first, functionalizing the silica surface with aminopropyldimethylethoxysilane (APDMES) by using saturated gas−solid reactions, and then immobilizing two different (tetramethylcyclopentadienyl)chlorosilanes, Me 2 Si(C 5 Me 4 H)Cl and MeHSi(C 5 Me 4 H)Cl, on the APDMES-functionalized silica by utilizing n -BuLi ( n -butyllithium). Zr(NMe 2 ) 4 was immobilized on the heterogeneous surfaces using the amine elimination reaction. The two heterogeneous monocyclopentadienylamido zirconium catalysts were characterized with 1 H, 13 C, and 29 Si solid-state NMR and FTIR spectroscopy and tested for ethylene polymerization.