As modifications of the effective catalyst precursor [dimethylsilanediylbis(benz[e]indenyl)]zirconium dichloride, the ansa-zirconocene complexes Me2Si(cyclopenta[c]phenanthryl)2ZrCl2, Me2Si(cyclopenta[l]phenanthryl)2ZrCl2, Me2Si(2-methylcyclopenta[l]phenanthryl)2ZrCl2, and Me2Si(2-methyltetrahydrobenz[e]indenyl)2ZrCl2 have been synthesized. When activated by methylaluminoxane (MAO), these complexes give highly active catalysts for the polymerization of propene to polymers with high isotacticities and molecular weights.

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Chiral, biphenyl-bridged metallocene complexes of general type biph(3,4-R2CsH2)2MCI2 (biph = 1,1'-biphenyldiyI) were synthesized and characterized. For the dimethyl-substituted titanocenes and zirconocenes (R CH 3 ; M Ti, Zr). preparations with increafed overall yields and an optical resolution method were developed. The bis(2-tetrahydroindenyI) complexes (R,R = (CH 2)4; M = Ti, Zr) were obtained by an alternative synthetic route and characterized with regard to their crystal structures. Syntheses of the phenyl-substituted derivatives (R C 6 H 5; M Ti, Zr) and of a chiral, methyl-substituted vanadocene complex (R CH 3; M V) are also reported.

In the presence of palladium C8lalysts, one of the two carbons attached to halogen in 2,2'-diiodobipbenyl couples with unsaturated organometallics, after which the other adds to the newly incorporated double bond. Spiro[cyc1opentene-l,9'-[9H]f\uorenc)s can be synthesized in this way.

Palladium-Catalyzed Coupling of 2,2'-Dihalobiaryls with MetalatedCyclopentenes. An Easy Synthesis for Spiro(cyclopentene-1,9'-(9H) fluorene)s.-The bromocyclopentene (II) or the bromocyclopentenone acetal (V) are lithiated and then transmetalated with zinc dichloride to generate the corresponding cyclopentenylzinc chlorides (III) and (VI) respectively. These react with the 2,2-diiodobiaryls (I) in the presence of a palladium (0) species to form the spiro compounds (IV) or (VII) and ( VIII) mentioned in the title. -(KATZ, T. J.; GILBERT, A. M.; HUTTENLOCH, M. E.; MIN-MIN, G.; BRINTZINGER, H. H.; Tetrahedron Lett. 34 (1993) 22, 3551-3554; Dep.