Development and innovation of metallocene catalysts: Polymerization of alpha-olefins (Spanish text)

Chapter 1. Ansa-zirconocenes, [Zr{lcub}1-Me 2Si(3-eta5-C9H5R)2{rcub}Cl 2] (R = Me, Et, Pr, Bu and Bz), have been prepared. The molecular structure of Meso-[Zr{lcub}1-Me2Si(3-eta5-C 9H5(CH3))2{rcub}Cl2], Meso-[Zr{lcub}1-Me2Si(3-eta5-C9H 5(CH2CH3))2{rcub}Cl2], Rac-[Zr{lcub}1-Me2Si(3-eta5-C9H 5(CH2CH3))2{rcub}Cl2], and Rac-[Zr{lcub}1-Me2Si(3-eta5-C9H 5(CH2CH2CH3))2{rcub}Cl2 ] have been determined by single crystal X-ray diffraction studies. Ethylene polymerization catalysis has been studied for complexes as a mixture of Meso and Rac isomers in the presence of methylaluminoxane (MAO) as an activator. Complexes reveal high activities and give rise to polyethylene with low molecular weights without the introduction of molecular hydrogen. The different elementary steps in the activation process of substituted complexes [Zr{lcub}1-Me2Si(3-eta5-C 9H5R)2{rcub}Cl2] (R = Me, Et, Pr, and Bu) by commercial methylaluminoxane (MAO) have been studied by UV/visible spectroscopy and correlated with ethylene polymerization. Addition of MAO in large excess yields a new intermediate in the mechanism of activation of metallocenes. This new intermediate has been amply studied. On the basis of our results, we can propose a new alternative route of mechanism for the metallocene activation when an excess of MAO is added.; Chapter 2. A series of substituted indene, C9H 7R-3 (R = CH2CH2CH2OSiMe3, CH2CH2CH2OCH2C6H 5, CH2CH2CH2OSiMe2 tBu), and ansa-indene compounds, {lcub}Me2Si(C 9H6R-3)2-1{rcub} (R = CH2CH2CH 2OSiMe3), {lcub}Me2Si(C9H6R-3)-1(C 5HMe4){rcub} (R = CH2CH2CH2OSiMe 3), CH2CH2CH2OCH2C 6H5, CH2CH=CH2, CH2CH 2CH2OSiMe2tBu), have been prepared. The lithium derivatives of these indene compounds were employed in the synthesis of the indenyl zirconium complexes, [Zr(eta 5-C9H6R-1)2Cl2] (R = CH 2CH2CH2OSiMe3), CH2CH 2CH2OCH2C6H5, CH2CH 2CH2OSiMe2tBu), rac[Zr{lcub}Me 2Si(eta5-C9H5R-3)2-1{rcub}Cl 2] (R = CH2CH2CH2OSiMe3), [Zr{lcub}Me2Si(eta5-C9H5R-3)1(eta 5-C5Me4{rcub}Cl2] (R = CH2CH 2CH2OSiMe3), CH2CH2CH 2OCH2C6H5, CH2CH=CH 2, CH2CH2CH2OSiMe2 tBu), and &sqbl0;Zr&cubl0;Me2Si&parl0;h 5-C9H5&parl0;CH2CH 2CH2O&parr0;-3&parr0;-1&parl0; h5-C5Me4&cubr0; Cl&sqbr0;. The molecular structure of &sqbl0;&cubl0;Zr&parl0;C9H6&parl0; CH2CH2CH2O&parr0;-1&parr0; Cl2&cubr0;2&sqbr0;, has been determined by single-crystal X-ray diffraction studies. The indenyl zirconium complexes have been immobilized on partially dehydroxilated SiO2, and these supported systems used to polymerize ethylene in the presence of methylaluminoxane. The catalytic activity of these compounds in both homogeneous and heterogeneous polymerization is reported.; Chapter 3. Both the symmetric and asymmetric ansa-ligand precursors Me2Ge(C5Me4H) 2 and Me2Ge(C5Me4H)(C5H 4R) (R = H, Me) and their lithium derivatives have been prepared. The Group 4 metal complexes containing germanium bridged ansa-ligands [M{lcub}Me2Ge(eta5-C5Me4) 2{rcub}Cl2] (M =Ti, Zr, Hf), [M{lcub}Me2Ge(eta 5-C5Me4)(eta5-C5H 4){rcub}Cl2] (M = Ti, Zr, Hf), and [M{lcub}Me2Ge(eta 5-C5Me4)(eta5-C5H 3Me){rcub}Cl2] (M = Ti, Zr, Hf) were prepared by the reaction of MCl4 and the corresponding lithiated ansa-derivative. The molecular structures of some of them were determined by single-crystal X-ray diffraction studies. Preliminary results for the catalytic activity of the Group 4 ansa-metallocene complexes in the polymerization of ethylene and propylene are reported.