Preparation and characterization of immobilized constrained-geometry hafnium complexes

Heterogeneous constrained-geometry hafnium complexes were prepared by ancho ring Hf(NMe2)(4) on a heterogenized ansa-cyclopentadienylamino ligand of ty pe (RN)R'R"Si(C5R4'''), surface 1: R = -O-Me2Si(CH2)(3); R', R", R''' = Me; surface 2: R = -O-Me2Si(CH2),; R', R''' = Me, R" = H. Preparation of the c onstrained-geometry catalyst ligand on silica surface was carried out in tw o steps: functionalizing of the silica surface with aminopropyidimethyletho xysilane (APDMES) by using saturated gas-solid reactions and immobilizing o f (tetramethylcyclopentadienyl)chlorosilanes, Me2Si(C5Me4H)Cl or MeHSi(C5Me 4H)Cl, on the functionalized silica by utilizing n-butyllithium (n-BuLi). H f(NMe2)(4) was immobilized on the heterogeneous surfaces by the amine elimi nation route. The complexes were characterized by H-1, C-13, and Si-29 soli d State NMR and FTIR spectroscopy. (C) 2000 Elsevier Science S.A. All right s reserved.