Issue 6, 2001
From the journal:

Journal of the Chemical Society, Dalton Transactions

Mono-guanidinate complexes of lanthanum: synthesis, structure and their use in lactide polymerization

Garth R. Giesbrecht,a   Glenn D. Whitenera  and  John Arnold*a  

* Corresponding authors

a Department of Chemistry, University of California, Chemical Sciences Division, Lawrence Berkeley National Laboratory, , Berkeley, USA

Abstract

La[N(SiMe3)2]3 reacted with 1,3-dicyclohexylcarbodiimide in refluxing toluene to yield the mono-guanidinate complex La[CyNC(N(SiMe3)2)NCy](N(SiMe3)2)21. Compound 1 is monomeric in solution; X-ray structural analysis reveals an unassociated complex in the solid state, with a four-coordinate lanthanum center. Complex 1 reacts with 2,6-di-tert-butylphenol (2 equivalents) in cold pentane to yield the bis(phenoxide) complex La[CyNC(N(SiMe3)2)NCy](OC6H3tBu2-2,6)2. X-Ray analysis indicates a similar structure to that of 1, with a four-coordinate lanthanum center coordinated by a single guanidinate ligand and two phenoxide groups. This compound catalyses the ring-opening polymerization of D,L-lactide to polylactide. Although high molecular weight polymer is obtained, polydispersities are broad and no control over the stereochemistry of the polymer is observed.

Graphical abstract: Mono-guanidinate complexes of lanthanum: synthesis, structure and their use in lactide polymerization

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Article information

DOI
https://doi.org/10.1039/B008164G
Article type
Paper
Submitted
10 Oct 2000
Accepted
22 Jan 2001
First published
01 Mar 2001

J. Chem. Soc., Dalton Trans., 2001, 923-927

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Mono-guanidinate complexes of lanthanum: synthesis, structure and their use in lactide polymerization

G. R. Giesbrecht, G. D. Whitener and J. Arnold, J. Chem. Soc., Dalton Trans., 2001, 923 DOI: 10.1039/B008164G

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