Electronic effects of Ziegler-Natta polymerization of propylene and ethylene using soluble metallocene catalysts

({eta}{sup 5}-5,6-X{sub 2}C{sub 9}H{sub 5}){sub 2}ZrCl{sub 2} catalysts (4a, X = H; 4b, X = CH{sub 3}; 4d, X = OCH{sub 3}; 4e, X = Cl) were investigated as catalysts for the polymerization of ethylene. In addition, polymerization of propylene and ethylene was studied by using corresponding racemic, ethylene-bridged analogues (5a, X = H; 5b, X = CH{sub 3}; 5d, X = OCH{sub 3}). Both the bridged and non-bridged catalysts were effective as catalysts for both ethylene and propylene polymerization, but the molecular weights were generally lower with the ethylene-bridged catalyst. 19 refs., 3 tabs.