文献类型：期刊文献

英文题名：Ring-opening polymerization of rac-lactide and α-methyltrimethylene carbonate catalyzed by magnesium and zinc complexes derived from binaphthyl-based iminophenolate ligands

作者：Huang, Miao;Pan, Chen;Ma, Haiyan[1]

机构：[1]E China Univ Sci & Technol, Shanghai Key Lab Funct Mat Chem, Shanghai 200237, Peoples R China; E China Univ Sci & Technol, Lab Organometall Chem, Shanghai 200237, Peoples R China

年份：2015

卷号：44

期号：27

起止页码：12420

外文期刊名：DALTON TRANSACTIONS

收录：;EI(收录号：20153201114463);WOS:【SCI-EXPANDED(收录号:WOS:000357398200041)】；

基金：This work was subsidized by the National Natural Science Foundation of China (NNSFC, 21074032 and 21474028), and the Fundamental Research Funds for the Central Universities (WK1214048, WD1113011). All the financial support is gratefully acknowledged. H. Ma also thanks the very kind donation of a Braun glove-box by the AvH Foundation.

语种：英文

外文关键词：Catalysts - Magnesium compounds - Zinc compounds - Polyesters - Chelation - X ray diffraction - Ligands

摘要：A series of racemic 2-[(2'-(dimethylamino) binaphthyl-2-ylimino) methyl]-4-R-2-6-R-1-phenols ((LH)-H-1-(LH)-H-6) were reacted with 1 equiv. of Mg[N(SiMe3)(2)](2) or Zn[N(SiMe3)(2)](2) to provide three heteroleptic magnesium silylamido complexes [(L4-6)MgN(SiMe3)(2)] (4a: R-1 = R-2 = cumyl; 5a: R-1 = CPh3, R-2 = Me; 6a: R-1 = CPh3, R-2 = Bu-t) and one heteroleptic zinc silylamido complex [(L-4)ZnN(SiMe3)(2)] (4b: R-1 = R-2 = cumyl). The molecular structures of complexes 4a, 4b and a homolepic zinc complex (L-5)(2)Zn (5b') were further confirmed by X-ray diffraction studies. In the solid state, the heteroleptic magnesium complex 4a has a four-coordinated metal core chelated by three donor atoms of the ligand and one bis(trimethylsilyl)amido group; however, the heteroleptic zinc complex 4b has a three-coordinated metal core chelated by two donor atoms of the ligand and one bis(trimethylsilyl) amido group, where the NMe2 group of the iminophenolate ligand is not coordinated to the zinc center. Magnesium complexes 4a-6a efficiently initiated the ring-opening polymerization (ROP) of rac-lactide in the presence/absence of 2-propanol, affording atactic polylactides in toluene and heterotactic bias polylactides in THF. Zinc complex 4b exhibited the highest stereoselectivity for the ROP of rac-lactide, affording substantially heterotactic polylactides in both solvents (P-r = 0.80-0.84). The kinetic studies of the polymerization revealed that the rate of polymerization is first-order in both monomer and catalyst concentrations. All these complexes were also very active in the polymerization of racemic alpha-methyltrimethylene carbonate (alpha-MeTMC). Detailed analyses using H-1 and C-13 NMR spectroscopy indicated the preferential ring-opening of alpha-MeTMC at the most hindered oxygen-acyl bond and zinc complex 4b gave the highest regioselectivity (X-reg = 0.98).