Effect of Titanium on Fluxional Behavior of Unbridged Metallocene Catalysts

Polo, Eleonora; Losio, Simona; Zecchi, Gaetano; Bertini, Fabio

doi:10.1002/marc.200400350

Cited by 4 publications

(1 citation statement)

References 26 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…After a systematic investigation on several 2-substituted bicyclic zirconocenes, we have successively investigated the effect of the change from zirconium to titanium on the most promising structures . Because the titanium center allows a closer interaction between the two bent cyclopentadienyl moieties, the effect of the substituents should have exerted a stronger influence on the interconversion speed between aspecific and isospecific isomers, thus favoring the formation of longer isotactic blocks.…”

Section: Introductionmentioning

confidence: 99%

Unbridged Zirconium and Titanium Metallocenes with Seven- or Eight-Saturated Fused-Ring Ligands: a Route for the Synthesis of Stereoblock Polypropene

Losio¹,

Zecchi²,

Bertini³

et al. 2005

Macromolecules

Self Cite

View full text Add to dashboard Cite

Unbridged zirconocene catalysts, where a seven-or eight-membered ring fused to a cyclopentadiene is associated with a phenyl substituent in position 2 (C 7Ph-Zr and C8Ph-Zr), were tested, under the same polymerization conditions, to produce polypropenes with microstructure, molecular properties, and thermal behavior similar to those prepared with (IndPh)2ZrCl2 (w-Zr), the "classical" Waymouth catalyst. Different results were obtained from the homologue titanium catalysts (C7Ph-Ti and C8Ph-Ti) and from the titanium benzyl derivative (C7Bn-Ti), which produced quite heterogeneous materials with broad molecular weight and that can be separated into fractions spanning from completely atactic to fractions characterized by the presence of long isotactic blocks. A quite interesting behavior is observed with the zirconium benzyl derivative C7Bn-Zr, which produces good yields of a polymer with narrow polydispersity, which, despite its rather high isotacticity, shows a hardly detectable melting peak and is completely ether soluble. Quite surprisingly, the same sample, after prolonged annealing, shows a narrow melting peak at low temperature (55-65 °C). This result, together with the X-ray analysis, is in favor of a quite homogeneous material, capable of giving crystallites of small size.

show abstract

Section: Introductionmentioning

confidence: 99%

Unbridged Zirconium and Titanium Metallocenes with Seven- or Eight-Saturated Fused-Ring Ligands: a Route for the Synthesis of Stereoblock Polypropene

Losio¹,

Zecchi²,

Bertini³

et al. 2005

Macromolecules

Self Cite

View full text Add to dashboard Cite

show abstract

Self‐Immobilizing Precatalysts: Norbornene‐Bridged Zirconium ansa‐Metallocenes

et al. 2008

Self Cite

View full text Add to dashboard Cite

Abstract:We report here the synthesis of new tethered biscyclopentadienyl and bisindenyl zirconocenes, bearing one unsaturation on the interannular bridge, and their use as self-immobilizing catalysts. They proved to be active catalysts towards ethylene polymerization in solution, with activities comparable to those displayed by commercial rac-Et-A C H T U N G T R E N N U N G (Ind) 2 ZrCl 2 . When tested as self-polymerization catalysts under suitable experimental conditions, they gave colored precipitates that, once reactivated with MAO, were significantly active in ethylene polymerization, although lower than those of the corresponding catalytic systems in solution. The molecular weights of the produced polymers were similar to those obtained with the same catalysts in solution, but their distribution resulted to be broader, with values typical of heterogeneous catalytic systems. From 13 C NMR studies we had the first spectroscopic evidence of the actual incorporation of a metallocene of this type into a polymeric chain.

show abstract

Substituted Ring‐Fused Yttrium Derivatives – X‐ray Crystal Structures of [(L′YCl₂·THF)₂LiCl·2THF] and [{L′YCl(OH)}₆·2THF] (L′ = 2‐Phenyl‐4,5,6,7,8‐hexahydroazulenyl)

et al. 2006

Self Cite

View full text Add to dashboard Cite

The reaction of lithium salts of ring‐fused ligands (L), where the ring fused to the cyclopentadienyl moiety is a saturated one (six, seven, or eight carbon atoms), with YCl3 in THF in 2:1 and 1:1 molar ratios affords complexes of formula [L2YCl]2 and [(LYCl2·THF)2LiCl·2THF], respectively. Here we report the synthesis, spectroscopic characterization, and X‐ray crystal structure of [(L′YCl2·THF)2LiCl·2THF] (L′ = 2‐phenyl‐4,5,6,7,8‐hexahydroazulenyl), together with the crystal structure of the hexameric species [{L′YCl(OH)}6·2THF], which was quite unexpectedly isolated during the attempted crystallization of the latter complex and is probably formed by partial hydrolysis of that complex. The activity of the new complexes towards ethylene and 1‐hexene polymerization reactions was also tested. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006)

show abstract

Effect of Titanium on Fluxional Behavior of Unbridged Metallocene Catalysts

Cited by 4 publications

References 26 publications

Unbridged Zirconium and Titanium Metallocenes with Seven- or Eight-Saturated Fused-Ring Ligands: a Route for the Synthesis of Stereoblock Polypropene

Unbridged Zirconium and Titanium Metallocenes with Seven- or Eight-Saturated Fused-Ring Ligands: a Route for the Synthesis of Stereoblock Polypropene

Self‐Immobilizing Precatalysts: Norbornene‐Bridged Zirconium ansa‐Metallocenes

Substituted Ring‐Fused Yttrium Derivatives – X‐ray Crystal Structures of [(L′YCl₂·THF)₂LiCl·2THF] and [{L′YCl(OH)}₆·2THF] (L′ = 2‐Phenyl‐4,5,6,7,8‐hexahydroazulenyl)

Contact Info

Product

Resources

About

Effect of Titanium on Fluxional Behavior of Unbridged Metallocene Catalysts

Cited by 4 publications

References 26 publications

Unbridged Zirconium and Titanium Metallocenes with Seven- or Eight-Saturated Fused-Ring Ligands: a Route for the Synthesis of Stereoblock Polypropene

Unbridged Zirconium and Titanium Metallocenes with Seven- or Eight-Saturated Fused-Ring Ligands: a Route for the Synthesis of Stereoblock Polypropene

Self‐Immobilizing Precatalysts: Norbornene‐Bridged Zirconium ansa‐Metallocenes

Substituted Ring‐Fused Yttrium Derivatives – X‐ray Crystal Structures of [(L′YCl2·THF)2LiCl·2THF] and [{L′YCl(OH)}6·2THF] (L′ = 2‐Phenyl‐4,5,6,7,8‐hexahydroazulenyl)

Contact Info

Product

Resources

About

Substituted Ring‐Fused Yttrium Derivatives – X‐ray Crystal Structures of [(L′YCl₂·THF)₂LiCl·2THF] and [{L′YCl(OH)}₆·2THF] (L′ = 2‐Phenyl‐4,5,6,7,8‐hexahydroazulenyl)