Rare earth catalysts possessing characteristics of cation-anion ion pair show advantages of adjusting electronegativity and steric hindrance of metal active sites, which can control the catalytic performance and stere...Rare earth catalysts possessing characteristics of cation-anion ion pair show advantages of adjusting electronegativity and steric hindrance of metal active sites, which can control the catalytic performance and stereoselectivity better than those of traditional metallocene and Ziegler-Natta catalysts in diene polymerization. In this work, a series of neodymium organic sulfonate complexes,Nd(CF_3SO_3)_3·x H_2O·y L(x, y: the coordination number; L refers to an organic electron donating ligand, such as acetylacetone(acac), isooctyl alcohol(IAOH), tributyl phosphate(TBP), etc.), have been synthesized to form the cationic active species in the presence of alkylaluminum such as Al(i-Bu)_3, AlEt_3, and Al(i-Bu)_2H, which display high activities and distinguishing cis-1,4 selectivities(up to99.9%) for the polymerization of butadiene. The microstructures, yield, molecular weight, and molecular weight distribution of the resulting polymer are well controlled by adjusting electronegativity/steric hindrance of the complexes. In addition, the kinetics, active species, and the possible process of polymerization are also discussed in this article.展开更多
Oxygen ligation is envisioned to provide a stable and distinctive coordination environment to the strongly oxophilic rare-earth metals. However, the well-defined dialkyl complexes bearing oxyanion ancillary ligand had...Oxygen ligation is envisioned to provide a stable and distinctive coordination environment to the strongly oxophilic rare-earth metals. However, the well-defined dialkyl complexes bearing oxyanion ancillary ligand had been rarely addressed for the instability of the complexes and the shortage of easily available ligands. Herein, we report the synthesis of phosphate ligated dialkyl yttrium complexes(PYR2) featuring a high stability and a tunable ligand. Treated with the borate reagent, the phosphate yttrium complex displays high activity and selectivity in the catalytic cis-1,4-polymerization of isoprene(up to 96.5%). Furthermore, using AlMe_(3) as an additive, the stereoselectivity switches to trans-1,4-polymerization(up to 92.0%).展开更多
基金the National Natural Science Foundation of China(Nos.51473156 and 51873203)Key Projects of Jilin Province Science and Technology Development Plan(Nos.2018020108GX and 20160204028GX)
文摘Rare earth catalysts possessing characteristics of cation-anion ion pair show advantages of adjusting electronegativity and steric hindrance of metal active sites, which can control the catalytic performance and stereoselectivity better than those of traditional metallocene and Ziegler-Natta catalysts in diene polymerization. In this work, a series of neodymium organic sulfonate complexes,Nd(CF_3SO_3)_3·x H_2O·y L(x, y: the coordination number; L refers to an organic electron donating ligand, such as acetylacetone(acac), isooctyl alcohol(IAOH), tributyl phosphate(TBP), etc.), have been synthesized to form the cationic active species in the presence of alkylaluminum such as Al(i-Bu)_3, AlEt_3, and Al(i-Bu)_2H, which display high activities and distinguishing cis-1,4 selectivities(up to99.9%) for the polymerization of butadiene. The microstructures, yield, molecular weight, and molecular weight distribution of the resulting polymer are well controlled by adjusting electronegativity/steric hindrance of the complexes. In addition, the kinetics, active species, and the possible process of polymerization are also discussed in this article.
基金the support from the Fudan Universitysupported by National Natural Science Foundation of China (Nos. 21890722 and 21950410519)National Natural Science Foundation of Tianjin (No. 19JCYBJC20100)
文摘Oxygen ligation is envisioned to provide a stable and distinctive coordination environment to the strongly oxophilic rare-earth metals. However, the well-defined dialkyl complexes bearing oxyanion ancillary ligand had been rarely addressed for the instability of the complexes and the shortage of easily available ligands. Herein, we report the synthesis of phosphate ligated dialkyl yttrium complexes(PYR2) featuring a high stability and a tunable ligand. Treated with the borate reagent, the phosphate yttrium complex displays high activity and selectivity in the catalytic cis-1,4-polymerization of isoprene(up to 96.5%). Furthermore, using AlMe_(3) as an additive, the stereoselectivity switches to trans-1,4-polymerization(up to 92.0%).
