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. (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 Jul 2019 16:30
URI: https://ueaeprints.uea.ac.uk/id/eprint/10514
DOI: 10.1021/om050309x

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