New [ONOO]-Type Amine Bis(phenolate) Ytterbium(II) and -(III) Complexes: Synthesis, Structure, and Catalysis for Highly Heteroselective Polymerization of rac-Lactide
Sheng Yang , Kun Nie , Yong Zhang , Mingqiang Xue , Yingming Yao , and Qi Shen *(沈琪)
Key Laboratory of Organic Synthesis of Jiangsu Province, College of Chemistry, Chemical Engineering and Materials Science, Dushu Lake Campus, Soochow University, Suzhou 215123, People’s Republic of China
Inorg. Chem. 2014, 53, 105–115
Two divalent ytterbium (YbII) complexes, 1 and 2, supported by new [ONOO]-type amine bis(phenolate) ligands La,b were synthesized by an amine elimination reaction of YbII(N(SiMe3)2)2(TMEDA) (TMEDA = tetramethylethylenediamine) with one equivalent of the ligand precursor. Two new trivalent ytterbium (YbIII) aryloxide complexes, 4 and 5, bearing [ONOO]-type amine bis(phenolate) ligands Lc and Ld were prepared by double-protonation reaction of Yb(C5H5)3THF with one equivalent of the ligand precursor, then one equivalent of phenol. Complexes 1 and 4 were found to be extremely active for controlled ROP of rac-LA. Complexes 1, 4 and 5 exhibited high stereoselectivity to give heterotactic polylactide with Pr ranging from 0.97 to 0.99.
链接： //pubs.acs.org/doi/abs/10.1021/ic401747n
