Preparation of Heterogeneous Constrained-Geometry Catalysts of Group 4 Transition Metals by Amine Elimination Reaction

Three heterogeneous constrained-geometry catalysts [(C 5 H 4 )SiMe 2 (N(CH 2 ) 3 SiMe 2 −O−)]M(NMe 2 ) 2 (M = Hf (catalyst 1 ), Zr (catalyst 2 ), and Ti (catalyst 3 ) were prepared by anchoring of metal amides (M(NMe 2 ) 4, M = Hf, Zr, or Ti) to a bifunctional ligand surface on SiO 2 . Preparation of the bifunctional ligand on silica surface was carried out in two steps. First the silica surface was functionalized with aminopropyldimethylethoxysilane (APDMES) by using saturated gas−solid reactions. Second a reaction of the amino groups on the silica surface with n -BuLi was carried out, producing lithiated amido groups, which were allowed to react further with chlorides of (cyclopentadienyl)dimethylchlorosilane (Me 2 Si(C 5 H 5 )Cl). Anchorage of the metal amides on the prepared surface was carried out by the amine elimination route. The heterogeneous catalysts were comprehensively characterized by 1 H, 13 C, and 29 Si solid state NMR and FTIR spectroscopy.