Rare earth metal-based catalysts for the polymerization of nonpolar
and polar monomers*
Jun Okuda**, Stefan Arndt, Klaus Beckerle, Kai C. Hultzsch, Peter Voth,
and Thomas P. Spaniol
Institut für Anorganische Chemie und Analytische
Chemie, Johannes Gutenberg-Universität Mainz, Duesbergweg 10-14,
D-55099 Mainz, Germany
Abstract: The synthesis of rare earth metal half-sandwich hydrido
complexes [Ln (h5:h1-C5Me 4SiMe2NCMe3) (THF) (µ-H) ]
2 (Ln = Y, Lu) through s-bond metathesis of the easily accessible
alkyl complexes [Ln (h5:h1-C5Me
4SiMe2NCMe3) (CH2 SiMe3) (THF) ]
was developed. The dimeric yttrium hydrido complexes are highly fluxional,
and a monomer-dimer equilibrium is present. They were tested as
single-site, single-component catalysts for the polymerization of ethylene
and styrene, as well as alkyl acrylate and acrylonitrile. The hydrido
complexes polymerize ethylene slowly and form isolable mono (insertion)
products with styrene. The yttrium n-alkyl complexes [Y (h5:h1-C5Me
4SiMe2NCMe3) (R) (THF) ] [R = (CH2) nCH3,
n = 3-9], prepared by the mono (insertion) of a-olefins, initiate
polymerization in a relatively controlled manner. Thus, styrene was
polymerized by the n-alkyl complex to give atactic polystyrenes with
somewhat enriched syndiotacticities.
* Lecture presented at the XIXth International Conference
on Organometallic Chemistry (XIX ICOMC) , Shanghai, China, 23-28 July
2000. Other presentations are published in this issue, pp. 205-376.
** Corresponding author
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