Preparation of heterogeneous constrained-geometry catalysts of group 4 transition metals by amine elimination reaction

Three heterogeneous constrained-geometry catalysts [(C5H4)SiMe2(N(CH2)(3)Si Me2-O-)]M(NMe2)(2) (M = Hf(catalyst 1), Zr (catalyst 2), and Ti (catalyst 3 ) were prepared by anchoring of metal amides (M(NMe2)(4), M = Hf, Zr, or Ti ) to a bifunctional ligand surface on SiO2. Preparation of the bifunctional ligand on silica surface was carried out in two steps. First the silica su rface was functionalized with aminopropyldimethylethoxysilane (APDMES) by u sing saturated gas-solid reactions. Second a reaction of the amino groups o n the silica surface with n-BuLi was carried out, producing lithiated amido groups, which were allowed to react further with chlorides of (cyclopentad ienyl)dimethylchlorosilane (Me2Si(C5H5)Cl). Anchorage of the metal amides o n the prepared surface was carried out by the amine elimination route. The heterogeneous catalysts were comprehensively characterized by H-1, C-13, an d Si-29 solid state NMR and FTIR spectroscopy.