New Bis(allyl)(diketiminato) and Tris(allyl) Lanthanide Complexes and Their Reactivity in the Polymerization of Polar Monomers

Sánchez-Barba, Luis F., Hughes, David, Humphrey, Simon M. and Bochmann, M. ORCID: https://orcid.org/0000-0001-7736-5428 (2005) New Bis(allyl)(diketiminato) and Tris(allyl) Lanthanide Complexes and Their Reactivity in the Polymerization of Polar Monomers. Organometallics, 24 (15). pp. 3792-3799.

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Abstract

The reaction of LnCl3(THF)n (Ln = La, n = 4; Ln = Y, Sm, Nd, n = 3) with 3 equiv of allylMgCl in THF/1,4-dioxane followed by crystallization in 1,4-dioxane/toluene proceeds in very high yields to give the tris(?3-allyl) complexes [La(?3-C3H5)3(?1-dioxane)]2(µ-dioxane) and [Ln(?3-C3H5)3(µ-dioxane)]8 (Ln = Y, 1 ; Sm, 2 ; Nd). Improved one-pot syntheses for the tris(?3-allyl) lanthanum and neodymium compounds are reported. The crystal structures of 1 and 2 show that the compounds consist of distorted square-pyramidal lanthanide centers in linear polymer chains. The reaction of [La(?3-C3H5)3(?1-dioxane)]2(µ-dioxane) and [Ln(?3-C3H5)3(µ-dioxane)]8 with the diketimine ligand 2-(2,6-diisopropylphenyl)amino-4-(2,6-diisopropylphenyl)imino-2-pentene (BDI-H) in THF at 60 °C generates cleanly the ß-diketiminato complexes Ln(?3-C3H5)2{?2-HC(MeCNAr)2} (Ar = 2,6-C6H3iPr2; Ln = La, 3 ; Y, 4 ; Sm, 5 ; Nd, 6 ) with propene elimination. The crystal structure of 5 shows a distorted tetrahedral SmN2(allyl)2 core, with the samarium atom positioned 1.438(4) Å out of the C3N2 ligand plane. All complexes are highly effective single-component catalysts for the ring-opening polymerization of e-caprolactone and rac-lactide. Polymer end group analysis shows that the polymerization process is initiated by allyl transfer to monomer.

Item Type: Article
Faculty \ School: Faculty of Science > School of Chemistry
Related URLs:
Depositing User: Rachel Smith
Date Deposited: 02 Nov 2010 17:48
Last Modified: 24 Oct 2022 02:28
URI: https://ueaeprints.uea.ac.uk/id/eprint/10514
DOI: 10.1021/om050309x

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