Advancements in boryl-bridged ansa-zirconocene chemistry.

摘要

In 1955 Karl Zeigler discovered that a trialkyl aluminum matrix containing traces of a transition metal could readily polymerize olefins. This was soon followed by Giulio Natta's finding that a titanium-aluminum system could polymerize propylene giving high molecular weight stereoregular polymers. These heterogeneous systems, though effective, fail to give the researcher the ability to dictate the physical properties of the polymers to much extent. In the mid 1980's Walter Kaminsky and Hans Brintzinger elucidated that the symmetry of the metallocene complex when activated by a Lewis acid could be used to influence the stereochemistry of a polymer. Their finding helped fuel further the investigation into the mechanism of the polymerization process. These investigations have led to a plethora of variations that can be employed to tune the metallocene catalyst system to produce polymers with desired physical properties. The focus of my research has been to develop a metallocene which incorporates a Lewis acid directly into the framework of the metallocene. This was accomplished by incorporating a boron atom into a bridge tethering the two cyclopentadienyl rings of the zirconocene. The placement of this Lewis acidic boron introduces unique properties into this system.