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A single zirconium-based constrained geometry catalyst (Me2Si(η1-C29H36)(η1-N-tBu)ZrCl2·OEt2/methylaluminoxane) has been employed to produce homopolymers of ethylene which contain degrees of branching unprecedented for early transition metal systems. A variable density of long branches is observed (10−50 branches per thousand carbon atoms) with strong dependences on both polymerization temperature and pressure. These branches are attributed to the exceptionally facile incorporation of long α-olefin macromonomers formed in situ via the usual β-hydride elimination of polymer chains. Additionally, a relatively constant low degree of ethyl branches is observed (∼5 branches per thousand carbon atoms) under all polymerization conditions; this is attributed to β-hydride transfer to monomer followed by immediate reinsertion of the coordinated olefin-terminated polymer into the formed metal−ethyl bond.

X-ray diffraction analyses of dimethyl ansa-metallocenes (CH3)2C(C5H4)(C29H36)M(CH3)2 (M = Zr or Hf) have revealed diffuse diffraction bands in the 0kl and h0l single-crystal reciprocal lattice images, but not in the hk0 plane. This is consistent with metallic disorder in two dimensions and constitutes a rare example of diffuse diffraction for an organometallic compound. The metal is apparently partitioned between two sites with a 60:40 occupancy ratio. Structural interpretation of the X-ray data is consistent with a 60:40 ratio of parallel/antiparallel (+z, −z) metallocene pillars dispersed in the x−y directions. Diffuse diffractionalbeit weakeris also observed for the half-metallocene (C29H37)Mn(CO)3, which occupies parallel/antiparallel pillars in an 80:20 ratio.

The octamethyloctahydrodibenzofluorenyl (Oct) ligand has been incorporated into twelve ansa -Oct-amido complexes having the general structures Me 2 Si(η 1 -C 29 H 36 )(η 1 -N- t Bu)MX 2 · L or Me 2 Si(η 5 -C 29 H 36 )(η 1 -N- t Bu)MX 2 (M = Zr or Hf): 2 (X = Cl, L = Et 2 O); 3 (X = Br, L = Et 2 O); 4 (X = Me, L = Et 2 O); 5 (X = Me, L = THF); 6 (X = CH 2 Ph); and 7 (X = CH 2 SiMe 3 ). The solid-state structures have been determined for seven of these complexes by X-ray crystallography, revealing η 5 -C 29 H 36 coordination for the ether-free, pseudotetrahedral species 6-Zr , 6-Hf , and 7-Zr , but η 1 -C 29 H 36 coordination for the ether-bound, trigonal bipyramidal species 2-Zr , 3-Zr , 3-Hf , and 5-Zr . The unusual η 1 -C 29 H 36 coordination was assigned because only one metal–carbon bond in each structure was in the range of 2.281–2.330 A; a second metal–carbon distance was found between 2.731 and 2.847 A; the remaining metal–carbon distances were found between 3.130 and 4.029 A. An increase in the hapticity of these and other Oct- and fluorenyl-containing compounds was correlated to a convergence in the carbon–carbon bond lengths within the relevant five-membered rings.

The structurally unique, sterically expanded eta1-fluorenyl-eta1-amido single-site precatalyst, Me2Si(eta1-N-tBu)(eta1-C29H36)ZrCl2.OEt2 (3), upon activation with methylaluminoxane (MAO), is remarkably active and constitutes the most syndioselective alpha-olefin polymerization catalyst system yet reported. 3/MAO affords as-prepared syndiotactic polypropylene with [rrrr]99% and unprecedented melting temperatures for the unannealed (165 degrees C) and annealed (174 degrees C) polymers. The activity of this system is 4 times that of the prototypical syndioselective catalyst Me2C(eta5-C5H4)(eta5-C13H8)ZrCl2/MAO. The high activity and syndioselectivity of 3/MAO can be extended to the production of syndiotactic poly(4-methyl-1-pentene) with a record melting temperature of 215 degrees C and [rrrr] = 97%.

The 14 A octamethyloctahydrodibenzofluorene moiety has been incorporated into a sterically expanded constrained geometry catalyst, Me2Si(eta1-C29H36)(eta1-N-tBu)ZrCl2.OEt2 (1). The solid-state structure suggests that the activated olefin polymerization catalyst is quite spatially accessible, rationalizing its extraordinary reactivity toward alpha-olefins. 1/MAO (MAO = methylaluminoxane) can be more reactive toward alpha-olefins than toward ethylene and exhibit activities that are linearly and continuously proportional to 4-methyl-1-pentene or 1-octene concentration in their copolymerizations with ethylene.

The structurally unique, sterically expanded η1-fluorenyl−η1-amido single-site precatalyst, Me2Si(η1-N-tBu)(η1-C29H36)ZrCl2·OEt2 (3), upon activation with methylaluminoxane (MAO), is remarkably active and constitutes the most syndioselective α-olefin polymerization catalyst system yet reported. 3/MAO affords as-prepared syndiotactic polypropylene with [rrrr] > 99% and unprecedented melting temperatures for the unannealed (165 °C) and annealed (174 °C) polymers. The activity of this system is 4 times that of the prototypical syndioselective catalyst Me2C(η5-C5H4)(η5-C13H8)ZrCl2/MAO. The high activity and syndioselectivity of 3/MAO can be extended to the production of syndiotactic poly(4-methyl-1-pentene) with a record melting temperature of 215 °C and [rrrr] = 97%.