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A series of Me 2 Si-bridged bis(2-Me-indenyl) ansa-zirconocenes containing N-pyrrolyl, N-indolyl, N-carbazolyl, and P-dibenzophospholyl substituents in position 4 of the indenyl moieties has been synthesized. Pd-catalyzed arylation of the azoles with 4-Br-2-Me-indene was used to synthesize the respective 4-(N-azolyl)indenes. 4-(P-Dibenzophospholyl)indene was obtained in high yield by reaction of 5-Cl-dibenzophosphole with (2-Me-inden-4-yl)MgBr. Some of the synthesized zirconocenes were characterized by X-ray crystallography. The raczirconocenes were tested in propylene polymerization in the presence of MAO or perfluoroarylborate activators. At 100 °C, the zirconocene rac-Me 2 Si[2-Me-4-(N-carbazolyl)indenyl] 2 ZrCl 2 /MAO afforded highly crystalline isotactic polypropylene with reasonable molecular weight (318 kDa) and a T m value of 157 °C determined by a remarkably low total number of stereo-and regioerrors, which makes it one of the most isoselective catalysts for high-temperature propylene polymerization.

The tantalum and niobium face-sharing dimers M2Cl6(SMe2)3 (I) have been found to react with SMe2 to form edge-sharing bioctahedra M2Cl6(SMe2)4 (II). The metal-metal bond lengths of the d1 2-d2 dimers increase by ca. 0.14 A in going from I to II, which raises a question as to the exact nature of the metal-metal bond in II [Ta-Ta = 2.829 (1) A; Nb-Nbav = 2.836 [2] A], Compounds of the type M2Cl6(dto)2 (III) (dto = 3,6-dithiaoctane) should be structurally similar to II and therefore were characterized by X-ray diffraction. The tantalum complex of III was found to have an average metal-metal bond length of 2.847 [6] A while that of the niobium analogue was surprisingly shorter, 2.688 (2) A, closely resembling the metal-metal bond length of I and those of other previously characterized edge-sharing bioctahedra of niobium and tantalum. The following crystallographic parameters were found for the four compounds: for Ta2Cl6(SMe2)4, space group P2\¡n with a = 10.324 (5) A, b = 11.110 (2) A, c = 10.446 (3) A, ß = 97.07 (3)e, and Z = 2; for Nb2Cl6(SMe2)4, space group P\ with a = 13.320 (2) A,b = 14.159 (2) A, c = 12.351 (3) A, a = 91.81 (2)°, ß = 92.06 (2)°, = 92.66 (2)°, and Z = 4; for Ta2Cl6(dto)2, space group Pi with a = 10.448

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In this work, we systematically studied the effects of substitutional modifications on the performance of the isospecific zirconocene-based catalyst family, Me2Si(2-Alk-4-(N-carbazolyl)Ind)ZrX2 (X = Cl, Me), wherein the progenitor (Alk =...