Rare Earth Half-Sandwich Catalysts for the Homo- and Copolymerization of Ethylene and Styrene

摘要: The synthesis of rare earth metal half-sandwich hydrido complexes [Ln(η5:η1-C5Me4SiMe2NCMe3)(THF)(μ-H)]2(Ln = Y, Lu, Yb, Er, Tb) through σ-bond metathesis the alkyl [Ln(η5:η1- C5Me4SiMe2NCMe3)(CH2SiMe3)(THF)], easily accessible by reaction amino-cyclopentadiene with [Ln(CH2SiMe3)3(THF)2], was developed. dimeric lanthanide are highly fluxional involving THF dissociation and cis-trans isomerization linked amidocyclopentadienyl ligand. presence a monomer-dimer equilibrium is suggested cross-over experiments. They were tested as single-site, single-component catalysts for polymerization ethylene, α-olefin, styrene, well acrylate acrylonitrile. polymerize ethylene slowly, whereas they form isolable mono(insertion) products α-olefins styrene. yttrium n-alkyl [Y(η5:η1,-C5Me4SiMe2NCMe3)(R)(THF)n] (R (CH2)nCH3, n 3-9), prepared α-olefins, initiate styrene in relatively controlled manner. Thus, polymerized in-situ formed n-hexyl complex to give atactic polystyrenes narrow molecular weight distributions somewhat enriched syndiotacticities. Sequential addition terf-butyl allows poly(styrene-block- tert-butyl acrylate).