Half-sandwich rare-earth-metal derivatives bearing pyrrolidinyl-functionalized cyclopentadienylligand: synthesis, characterization and catalysis in syndiospecific polymerization of styrene

Abstract

One-pot reaction of LnCl₃ with 1 equivalent of C₅Me₄SiMe₂NC₄H₈Li followed by addition of 2 equivalents of allylmagnesium chloride C₃H₅MgCl or LiN(SiHMe₂)₂ in THF at room temperature afforded the half-sandwich rare-earth-metal bis(η³-allyl) complexes (C₅Me₄SiMe₂NC₄H₈)Ln(η³-C₃H₅)₂ (Ln = Sc (1), Y (2), Lu (3)) and the half-sandwich rare-earth-metal bis(silylamide) complexes (C₅Me₄SiMe₂NC₄H₈)Ln[N(SiHMe₂)₂]₂ (Ln = Sc (4), Y (5), Lu (6)), respectively. All these complexes were well-characterized by elemental analysis, FT-IR spectroscopy, NMR spectroscopy and X-ray crystallography. The binary catalyst systems 1–3/[Ph₃C][B(C₆F₅)₄] and the ternary catalyst systems 1–6/[Ph₃C][B(C₆F₅)₄]/AlⁱBu₃ in toluene at room temperature showed activity toward the syndiospecific polymerization of styrene.