6533b82afe1ef96bd128b69c

RESEARCH PRODUCT

Rare earth metal-based catalysts for the polymerization of nonpolar and polar monomers

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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.