Differences of zirconocenes and hafnocenes

In this work new C2-symmetric ansa-metallocene dichlorides for the formation of high isotacticity, high melting polypropylene at increased polymerization temperatures are presented. Therefore a versatile synthesis route was developed leading to an ultimate control of the microstructure of the resulting polypropylene just by ligand design. These complexes are able to produce polypropylene with extremely high stereo- and regioregularity thus affording polypropylene with the so far highest reported melting transition (ex-reactor) of 171 °C. Furthermore C1-symmetric ansa-metallocene dichlorides for the formation of elastic polypropylene were investigated with respect to their applicability at high polymerization temperatures. Especially the different polymerization behavior of the respective zirconocene and hafnocene dichlorides at varying polymerization temperature was shown to be a result of their different transfer reactions.