Syntheses, Characterization, and Ethylene Polymerization of Titanium Complexes with Double-Duty Tridentate [ONN] Ligands
摘要:
A series of titanium complexes containing the tridentate [CNN] ligands La-Lf were synthesized and characterized. The ligands Lb (8-quinolinolato-CH2NHAr; Ar = 2,6-dasopropylphenyl) has been prepared by the reduction of the corresponding imino-quinolinol compound La (8-quinolinolato-CH=NAr; Ar = 2,6-diisopropylphenyl) with LiAlH4 in high yield. Ligands Lc-Lf were synthesized by a procedure similar to that used to prepare ligand Lb. Reaction of TiCl4 with imino-quinolinol ligand La affords the six-coordinate trichloride titanium complex 1. The selective synthesis of tri- and dichlorotitanium complexes containing ligand Lb was achieved by changing the base for deprotonation. When it is deprotonated by NaH, ligand Lb can be used as a tridentate monoanionic ligand to synthesize trichlorotitanium complex 2. While deprotonated by ''BuLi, it can be used as a tridentate dianionic ligand to synthesize dichlorotitanium complex 3. Other dichlorotitanium complexes 4-7 were synthesized by a procedure similar to that used to prepare complex 3. All complexes have been characterized by H-1 NMR spectra and elemental analysis. The molecular structures of ligand Lb and complex 1 have been characterized by single-crystal X-ray diffraction analyses. XANES and EXAFS spectroscopy performed on the representative complexes 2 and 3 reveals the different coordination geometries. When they are activated by excess methylaluminoxane (MAO), all of the titanium complexes can be used as catalysts for ethylene polymerization and exhibit moderate to good activities. It was found that the catalytic behaviors of the title complexes were highly affected by the coordination entironment of the metal center and the effect of substituent groups on ligands.
Methylaluminium 8-quinolinolates: synthesis, characterization and use in ring-opening polymerization (ROP) of ε-caprolactone
摘要:
2-(2,6-R苯基亚氨基)喹啉-8-醇(L1~L5, L1: R = Me, L2: R = Et, L3: R = iPr, L4: R = Cl, L5: R = F)与Me3Al的化学计量反应以良好收率得到了二聚体铝配合物[Me2AlL]2 (1~5)。相比之下,2-(1-(2,6-R-苯基亚氨基)丙基)喹啉-8-醇(L6~L10, L6: R = Me, L7: R = Et, L8: R = iPr, L9: R = Cl, L10: R = F)与Me3Al的化学计量反应得到了单核铝配合物Me2AlL (6~10),同时伴随着副产物Me2AlL·Me3Al (11~15)的生成。所有甲基铝配合物均通过NMR光谱、元素分析进行了表征,配合物3、6和8的分子结构由单晶X射线衍射确定。铝化合物1~5对ε-己内酯的开环聚合无论有无BnOH的存在均无活性。相反,在BnOH存在下,单核铝化合物6~10能高效引发ε-己内酯的开环聚合;聚合过程表现出生长方式。
Syntheses, Characterization, and Ethylene Polymerization of Half-Sandwich Zirconium Complexes with Tridentate Imino−Quinolinol Ligands
作者:Ping Hu、Fosong Wang、Guo-Xin Jin
DOI:10.1021/om101059v
日期:2011.3.14
A series of half-sandwich zirconium complexes with imino-quinolinol ligands have been synthesized and characterized. The catalytic behaviors of these complexes toward ethylene polymerization were investigated in the presence of methylaluminoxane (MAO) as a cocatalyst. The catalytic behaviors were highly affected by the substituent in both cyclopentadienyl and imino-quinolinol ligands. The Cp analogue complexes CpZr[ONNR]Cl-2 (1a-e) exhibited high activities up to 1.34 x 10(7) g of PE (mol of Zr)(-1) h(-1), whereas the Cp* analogue complexes Cp*Zr[ONNR]Cl-2 (2a-e) also showed moderate activities for ethylene polymerization.
POLYMERISATION OF ETHYLENE AND ALPHA-OLEFINS WITH IMINO-QUINOLINOL COMPLEXES