Zinc, aluminum and group 3 metal complexes of sterically demanding naphthoxy-pyridine ligands: Synthesis, structure, and use in ROP of racemic lactide and β-butyrolactone

Yulia Chapurina (1) , Thierry Roisnel (1) , Jean-François Carpentier (1) , Evgeny Kirillov (1)

1 ISCR - Institut des Sciences Chimiques de Rennes

New potentially tridentate, bulky ortho-Ph3Si-substituted naphthol-pyridine proligands a–f were synthesized and introduced onto zinc, aluminum and group 3 metal centers (M = Sc, Y, La) using straightforward one-step alkane or amine elimination protocols. The solid-state structures of these mononuclear zinc (1a, 1c, 1d, 2c and 2e) and aluminum (3c) complexes were determined by single-crystal X-ray diffraction studies, while the solution structures were established using 1H, 13C{1H} and 29Si/29Si{1H} (when appropriate) NMR spectroscopy. For all complexes, only one species (isomer) of C1 symmetry was observed by NMR spectroscopy in the broad temperature range. Most of these complexes are effective initiators for the ring-opening polymerization (ROP) of racemic lactide (rac-LA) at 25–100 °C, affording poly(lactides)s (PLAs) generally with unimodal dispersities and molecular weights in good agreement with calculated values. An yttrium complex (4e) proved the most active (TOF = 1840 mol(LA) mol(Y)−1 h−1 at 25 °C) and yielded heterotactic-enriched PLAs (Pr up to 0.80) in toluene, while atactic PHBs were formed in the ROP of racemic β-butyrolactone (rac-BBL) under the same conditions.

Mots clés: Zinc; Lanthanides; Catalysis; Lactide; Aluminum; Ring-opening polymerization

Domaines: Matériaux

Yulia Chapurina, Thierry Roisnel, Jean-François Carpentier, Evgeny Kirillov. Zinc, aluminum and group 3 metal complexes of sterically demanding naphthoxy-pyridine ligands: Synthesis, structure, and use in ROP of racemic lactide and β-butyrolactone. Inorganica Chimica Acta Reviews, 2015, 431, pp.161-175. ⟨10.1016/j.ica.2014.11.002⟩. ⟨hal-01091458⟩