1369966-40-4Relevant academic research and scientific papers
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.
