Reversible Chain Transfer between Organoyttrium Cations and Aluminum : Synthesis of Aluminum-Terminated Polyethylene with Extremely Narrow Molecular-Weight Distribution

Title data

Kretschmer, Winfried ; Meetsma, Auke ; Hessen, Bart ; Schmalz, Thomas ; Qayyum, Sadaf ; Kempe, Rhett:
Reversible Chain Transfer between Organoyttrium Cations and Aluminum : Synthesis of Aluminum-Terminated Polyethylene with Extremely Narrow Molecular-Weight Distribution.
In: Chemistry : a European Journal. Vol. 12 (2006) Issue 35 . - pp. 8969-8978.
ISSN 1521-3765
DOI: https://doi.org/10.1002/chem.200600660

Official URL:

Abstract in another language

Aminopyridinato-ligand-stabilized organoyttrium cations are accessible in very good yield through alkane elimination from trialkyl yttrium complexes with sterically demanding aminopyridines, followed by abstraction of one of the two alkyl functions using ammonium borates. At 80 °C and in the presence of small amounts of aluminum alkyl compounds, very high ethylene polymerization activities are observed if very bulky aminopyridinato ligands are used. During these polymerizations a reversible polyethylene chain transfer is observed between the organoyttrium cations and aluminum alkyls. The chain-transfer catalyst system described here is able to produce relatively long-chain (up to 4000 g mol−1) Al-terminated polyethylene with a molecular-weight distribution <1.1. In the synthesis of higher molecular PE a slight increase in polydispersity with increasing chain length (15 600 g mol−1, ∼1.4) is observed owing to reduced reversibility caused by higher viscosity and precipitation of polymer chains (temperature of 80–100 °C).

Further data

Item Type:	Article in a journal
Refereed:	Yes
Keywords:	aluminum; chain transfer; lanthanides; polymerization; yttrium
Institutions of the University:	Faculties > Faculty of Biology, Chemistry and Earth Sciences > Department of Chemistry Faculties > Faculty of Biology, Chemistry and Earth Sciences > Department of Chemistry > Chair Inorganic Chemistry II > Chair Inorganic Chemistry II - Univ.-Prof. Dr. Rhett Kempe
Result of work at the UBT:	Yes
DDC Subjects:	500 Science > 540 Chemistry
Date Deposited:	02 Mar 2026 07:48
Last Modified:	02 Mar 2026 07:48
URI:	https://eref.uni-bayreuth.de/id/eprint/96435