BRIDGED BIS (FLUORENYL) COMPLEXES OF ZIRC ONIUM AND HAFNIUM AS HIGHLYREACTIVE CATALYSTS IN HOMOGENEOUS OLEFIN POLYMERIZATION - MOLECULAR-STRUCTURES OF (C13H9-C2H4-C13H9) AND (ETA(5)ETA(5)-C13H8-C2H4-C13H8)ZRCL2

The stepwise reaction of lithium fluorenyl and 1,2-dibromo-ethane give s 1,2-difluorenylethane (1). The reaction of 1 with MeLi (1:2) yields the dianion (C13H8-C2H4-C13H8)2- that can be reacted with MCl4 (M = Zr , Hf) to yield the ansa-metallocene complexes (C13H8-C2H4-C13H8)MCl2 ( M = Zr (2), Hf (3)). The complexes 2 and 3 are the first ansa-bis(fluo renyl) complexes of a group 4 metal. Especially 2, in combination with methylaluminoxane (mao) shows an extremely high activity as a homogen eous ethylene polymerization catalyst. Compound 1 and complex 2 were c haracterized by X-ray diffraction studies.