Oxygen-Containing, Asymmetric “Dual-Side” Zirconocenes: Investigations on a Reversible Chain Transfer to Aluminum

Abstract

A series of new oxygen-substituted, asymmetric zirconocene dichlorides (rac-{1-[5,6-(ethylenedioxy)-2-methyl-1-η 5 -indenyl]-2-(9-η 5 -fluorenyl)ethane}zirconium dichloride (3a), rac-{1-[5,6-(ethylenedioxy)-2-methyl-1-η 5 -indenyl]-2-(9-η 5 -fluorenyl)ethane}dimethylzirconium (3b) and rac-{[5,6-ethylenedioxy)-2-methyl-1-η 5 -indenyl](9-η 5 -fluorenyl)dimethylsilane}zirconium dichloride (3c)} have been prepared and their polymerization behavior was investigated in dependence of monomer concentration, temperature and catalyst activation. The presence of oxygen substituents on the indenyl ring results in a strong increase of polymerization activities

Catalytic Polymerization and Post Polymerization Catalysis Fifty Years After the Discovery of Ziegler's Catalysts

“…[96] In Rieger's oxygen containing, ''dual side'' zirconocenes the examination of poly(propylene) microstructures with respect to stereoerror formation as well as the role of the Al/Zr molar ratio implies that reversible chain transfer to aluminium takes place. [97] Chien used iso-and syndiospecific ansa-metallocenes, activated with AliBu 3 /Ph 3 C þ B(C 6 F 5 ) 4 À to polymerize propylene with this binary catalyst system where the activity profiles of both iso-and syndiospecific catalysts were very similar. The resulting polymers were quite different from reactor blends of isotactic and syndiotactic poly(propylene)s. Although a bimodal molecular weight distribution was obtained, all fractions of the size exclusion chromatography (SEC) contained both isotactic and syndiotactic sequences, as proven by FT-IR measurements coupled with SEC.…”

C1‐Symmetric Heterocyclic Zirconocenes as Catalysts for Propylene Polymerization, 2

“…[20] Ind-Flu ligands bearing heterocycles condensed to the 4,5, 5,6, or 6,7 positions of indene have also been reported [21,22] (Table 2).…”

“…[22] [22] [22] [21] [21] [21] C 1 -Symmetric Heterocyclic Zirconocenes as Catalysts for Propylene Polymerization, 2 discussed in the section '' 13 C NMR Analysis and Correlation with Thermal and Solubility Data. ''…”

Catalytic activity of phenyl substituted cyclopentadienyl neodymium complexes in the ethylene oligomerization process

“…Indeed, regular zirconocenes, containing the CH 3 O-or -O-CH 2 -CH 2 -O-substituent in the 6-memered ring of an indenyl ligand, usually possess poor catalytic activity in olefin polymerization processes [30][31][32]. Only introduction of bulky substituents in the ortho-position to the methoxy group allows to obtain truly catalytically active zirconocene [33,34].…”