Bis(oxazolinyl)phenyl-ligated rare-earth-metal complexes: highly regioselective catalysts for cis-1,4-polymerization of isoprene.
Bis(oxazolinyl)phenyl-ligated rare-earth-metal complexes: highly regioselective catalysts for cis-1,4-polymerization of isoprene.
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DOI：
10.1021/ic300976p
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发表时间：
2013-03
影响因子：
4.6
通讯作者：
Yutian Pan;Tieqi Xu;Guan-Wen Yang;Kun Jin;Xiao‐Bing Lu
中科院分区：
文献类型：
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作者：
Yutian Pan;Tieqi Xu;Guan-Wen Yang;Kun Jin;Xiao‐Bing Lu
在四氢呋喃溶剂中，通过[（S，S）-Phebox-（i）Pr]Li与LnCl 3的金属转移反应，合成了NCN-钳形（S，S）-2，6-双（4 '-异丙基-2'-恶唑啉基）苯基配位稀土金属二氯化物[（S，S）-Phebox-（i）Pr] LnCl 2（THF）2（Ln = Sc（1）; Y（2）; Dy（3）; Ho（4）; Tm（5）; Lu（6））。有趣的是，通过相同的方法处理LaCl 3生成三（配体）镧配合物[（S，S）-Phebox-（i）Pr]3La（7）。配合物1、2、3和7的分子结构通过单晶X-射线衍射研究确定。钳形配体（S，S）-Phebox-（i）Pr与中心金属离子采用κC：κN：κN'三齿配位模式。在[PhNHMe 2][B（C6 F5）4]和Al（i）Bu 3的活化下，配合物2-5对异戊二烯聚合表现出很高的催化活性和98%以上的顺式-1，4-选择性，而配合物1和6对该反应无活性。当使用由配合物2、[PhNHMe 2][B（C6 F5）4]和Al（i）Bu 3组成的催化体系进行异戊二烯聚合时，所得聚合物具有高达99.5%的高顺式-1，4-选择性。反应温度对区域选择性影响不大，在80 °C时仍保持较高的顺式-1，4-选择性。
NCN-pincer (S,S)-2,6-bis(4'-isopropyl-2'-oxazolinyl)phenyl-ligated rare-earth-metal dichlorides [(S,S)-Phebox-(i)Pr]LnCl2(THF)2 (Ln = Sc (1); Y (2); Dy (3); Ho (4); Tm (5); Lu (6)) were synthesized via transmetalation between [(S,S)-Phebox-(i)Pr]Li and LnCl3 in THF solvent. Interestingly, treatment of LaCl3 by the same method generated tris(ligand) lanthanum complex [(S,S)-Phebox-(i)Pr]3La (7). Molecular structures of complexes 1, 2, 3, and 7 were established by single-crystal X-ray diffraction study. Pincer ligand (S,S)-Phebox-(i)Pr adopts a κC:κN:κN' tridentate coordination mode to the central metal ion. Upon activation with [PhNHMe2][B(C6F5)4] and Al(i)Bu3, complexes 2-5 exhibited highly catalytic activities and more than 98% cis-1,4-selectivity for isoprene polymerization while complexes 1 and 6 were inactive for this reaction. When use of the catalyst system consisted of complex 2, [PhNHMe2][B(C6F5)4], and Al(i)Bu3 for isoprene polymerization, the resultant polymer has a high cis-1,4-selectivity up to 99.5%. The reaction temperature had little effect on the regioselectivity, and high cis-1,4-selectivity almost remained even at 80 °C.