| Strategies for designing specified Group IV ansa-metallocene olefin polymerization catalysts have been provided. In efforts to suppress the formation of undesired meso isomers of ansa-bis(indenyl)metallocene complexes, the previously enantiotopic faces of indenyl ligands were converted into diastereotopic faces by placing a chirality on the bridging atom, thus favoring the formation of an optically active, C;A variety of 25 new organic ligands and organometallic complexes have been synthesized in this study. A thermal diastereomerization of indenylsilane ligands has been discovered and studied by the dynamic NMR technique. By carefully tuning the electronics and steric hindrance of ligand frameworks, five series of catalytic systems have been generated; they are a silacyclobutane-bridged bis(indenyl)zirconocene, a tetraphenylgermacyclopentadiene-bridged bis(indenyl)zirconocene derived from a stereoselective synthesis with aid of a MM calculation, a heptane-soluble homogeneous zirconocene catalyst with bis(menthoxy)silylene as the bridge, C;Polymerization catalysis has been carried out, leading to isospecific, syndio-specific or non-stereospecific polymerizations of... |
