1369966-40-4Relevant articles and documents
Synthesis and characterization of lanthanide amides bearing aminophenoxy ligands and their catalytic activity for the polymerization of lactides
Zhang, Jie,Qiu, Jinshui,Yao, Yingming,Zhang, Yong,Wang, Yaorong,Shen, Qi
, p. 3138 - 3148 (2012)
A series of neutral lanthanide complexes supported by aminophenoxy ligands were synthesized, and their catalytic behavior in the polymerization of l-lactide and rac-lactide was explored. The amine elimination reactions of equimolar amounts of Ln[N(TMS)2]3(ν-Cl)Li(THF) 3 and aminophenol [HONH]1 {[HONH]1 = 2,6-Me2-C6H4NHCH2(3,5- tBu2-C6H2-2-OH)} in toluene gave the dimeric lanthanide complexes {[ON]1Ln[ONH]1}2 (Ln = La (1), Nd (2)), whereas the similar reactions of La[N(TMS) 2]3(THF)2 or Ln[N(TMS)2] 3(ν-Cl)Li(THF)3 (Ln = Nd, Sm) with the aminophenols [HONH]2 {[HONH]2 = (μ-OCH3-C 6H4)NHCH2(3,5-tBu2-C 6H2-2-OH} and [HONH]3 {[HONH]3 = (NC5H4)NHCH2(3,5-tBu 2-C6H2-2-OH)} generated the neutral aminophenoxy lanthanide amides {[ON]2Ln[N(TMS)2]} 2 [Ln = La (3), Nd (4), Sm (5)] and {[ON]3Ln[N(TMS) 2](THF)}2 [Ln = La (6), Nd (7), Sm (8)], respectively, in high isolated yields. These complexes have been fully characterized. X-ray structural determination revealed that complexes 1 and 2 have unsolvated centrosymmetric dimeric structures, in which one hydrogen atom belonging to the amino group of the ligand is reserved. Complexes 3-5 are isostructural and have an unsolvated dimeric structure. The coordination geometry around each of the lanthanide metal atoms can be described as a distorted trigonal bipyramid. Complexes 6 and 7 have a solvated dimeric structure, and the lanthanide metal centers have distorted capped trigonal-prismatic geometries. It was found that complexes 3-8 are highly efficient initiators for the ring-opening polymerization of l-lactide and rac-lactide, affording polymers with high molecular weights.
