Synthesis and characterization of carbon-bridged bis(phenolate) lanthanum alkoxides and their catalytic behavior for the polymerization of L-lactide

• Published in: Chinese science bulletin Vol. 57; no. 34; pp. 4442 - 4447
• Main Authors: Li, BaoXia, Qi, RuiPeng, Yao, YingMing, Zhang, Yong, Shen, Qi
• Format: Journal Article
• Language: English
• Published: Heidelberg Springer-Verlag 01.12.2012; SP Science China Press
• Subjects: catalysts; Chemistry/Food Science; Earth Sciences; Engineering; Humanities and Social Sciences; lanthanum; Life Sciences; multidisciplinary; organic compounds; oxides; Physics; polymerization; Science; Science (multidisciplinary); bis(phenolate) ligands; synthesis; polymerization; lactide; alkoxide; organolanthanide complex
• ISSN: 1001-6538; 1861-9541
• DOI: 10.1007/s11434-012-5330-9

Four lanthanum alkoxides stabilized by a carbon-bridged bis(phenolate) ligand were synthesized and their catalytic behavior for the ring-opening polymerization of L-lactide was explored. Reactions of [(MBMP)LaCp(THF)₂] (MBMP²⁻ = 2,2′-methylene-bis(6-tert-butyl-4-methyl phenoxo)) with HOCH₂Ph, HOCH₂CF₃, HOCH(CH₃)₂, and HOCH₂CH₂N(CH₃)₂, respectively, in a 1:1 molar ratio in THF gave the dimeric lanthanum alkoxo complexes [(MBMP)Ln(Sm-OR)(THF)₂]₂ (OR = OCH₂Ph (1), OCH₂CF₃ (2), OCH(CH₃)₂ (3), OCH₂CH₂N(CH₃)₂ (4)]. These complexes were well characterized, and the definitive molecular structure of complex 1 was determined. It was found that complexes 1 to 4 are efficient initiators for the ring-opening polymerization of L-lactide. The structure of the alkoxo groups has a significant effect on the catalytic behavior, and complex 2 can initiate L-lactide polymerization in a controlled manner.