BRIDGED BORATABENZENE ZIRCONIUM COMPLEXES - ANALOGS OF THE ANSA-ZIRCONOCENE POLYMERIZATION CATALYSTS

Ethylene-bridged ,N-diisopropyl-1-aminoboratabenzene-4-yl)zirconium di chloride (5a), dimethylsilyl-bridged ,N-diisopropyl-1-aminoboratabenze ne-4-yl)zirconium dichloride (7a), and dimethylmethylene-bridged ,N-di isopropyl-1-aminoboratabenzene-4-yl)zirconium dichloride (6a) have bee n prepared. X-ray crystal structures of the dimethyl derivatives of 5 and 7 show that the complexes closely resemble the corresponding ansa- zirconocenes. When activated by excess methylaluminoxane, 5a, ga, and 7a are catalysts for the polymerization of olefins.