Ligand Recognition Processes in the Formation of Homochiral C3‐Symmetric LnL3 Complexes of a Chiral Alkoxide |
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| Authors: | Polly?L Arnold Prof?Dr Jean‐Charles Buffet Robert Blaudeck Slawomir Sujecki Dr Claire Wilson Dr |
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| Institution: | 1. School of Chemistry, Joseph Black Building, University of Edinburgh, West Mains Road, Edinburgh, EH9 3JJ (UK), Fax: (+44)?131‐650‐6453;2. School of Chemistry, University of Nottingham, University Park, Nottingham NG7 2RD (UK);3. School of Electronic and Electrical Engineering, University of Nottingham, University Park, Nottingham NG7 2RD (UK);4. Rigaku Europe, Chaucer Business Park, Watery Lane, Sevenoaks, Kent TN15 6QY (UK) |
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| Abstract: | The reaction of a chiral racemic bidentate ligand HL1 (tBu2P(O)CH2CH(tBu)OH) with mid to late trivalent lanthanide cations affords predominantly homochiral lanthanide complexes (RRR)‐Ln(L1)3] and (SSS)‐Ln(L1)3]. A series of reactions are reported that demonstrate that the syntheses are under thermodynamic control, and driven by a ligand ‘self‐recognition’ process, in which the large asymmetric bidentate L1 ligands pack most favourably in a C3 geometry around the lanthanide cation. The synthesis of bis(L1) adducts Ln(L1)2X] (X=N(SiMe3)2, OC6H3tBu‐2,6) is also reported. Analysis of the diastereomer mixtures shows that homochiral (L1)2 complexes are favoured but to a lesser extent. The complexes Ln(L1)3 and Ln(L1)2(OC6H3tBu‐2,6)] have been studied as initiators for the polymerization of ε‐caprolactone and its copolymer with lactide, glycolide and its copolymer with lactide, and ε‐caprolactam. |
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| Keywords: | biorenewable monomers lanthanides ligand self‐recognition O ligands polylactic acid polymerization |
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