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Highly cis-1,4-selective living polymerization of 1,3-conjugated dienes and copolymerization with ε-caprolactone by bis(phosphino)carbazolide rare-earth-metal complexes

机译:1,3-共轭二烯的高顺式1,4-选择性活性聚合及双(膦基)咔唑内酯稀土金属配合物与ε-己内酯的共聚合

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摘要

Bis(phosphino)carbazole, HL (HL = 3,6-(tBu)_2-1,8-(PPh _2)_2-carbazole), reacted with rare-earth-metal tris(aminobenzyl) complexes (Ln(CH_2C_6H_4N(Me) _2-o)_3) to afford the first PNP-carbazolide rare-earth-metal bis(alkyl) complexes, LLn(C_6H_4CH _2N(Me)_2)_2 (Ln=Y (1), Sc (2), Er (3)). The yttrium complex 1 was characterized by X-ray diffraction analysis as a solvent-free monomer, in which the carbazolide ligand coordinates to the Y ~(3+) ion in a κP:κN:κP′-tridentate mode and the two aminobenzyl groups coordinate to the Y~(3+) ion in η~1C:κN-bidentate modes. Complexes 1-3 combined with [Ph_3C][B(C_6F_5)_4] gave cationic catalyst systems that initiated cis-1,4-polymerizations of 1,3-conjugated dienes with high activities. Especially, the system 1/[Ph_3C][B(C _6F_5)_4] displayed excellent cis-1,4-selectivity (>99%) and living mode at a broad range of polymerization temperatures (0-80 °C). Remarkably, the living yttrium-polydiene active species could further initiate the ring-opening polymerization of ε-caprolactone to give selectively poly(cis-1,4-diene)-b-polycaprolactone block copolymer with controllable molecular weight (Mn = (10-70) - 104) and narrow polydispersity (PDI = 1.15-1.47).
机译:双(膦)咔唑,HL(HL = 3,6-(tBu)_2-1,8-(PPh _2)_2-咔唑),与稀土金属三(氨基苄基)配合物(Ln(CH_2C_6H_4N(Me )_2-o)_3)生成第一个PNP-咔唑类稀土金属双(烷基)络合物LLn(C_6H_4CH _2N(Me)_2)_2(Ln = Y(1),Sc(2),Er( 3))。钇配合物1通过X射线衍射分析表征为无溶剂单体,其中咔唑配体以κP:κN:κP'-三齿模式和两个氨基苄基配位至Y〜(3+)离子在η〜1C:κN双齿模式下与Y〜(3+)离子配位。配合物1-3与[Ph_3C] [B(C_6F_5)_4]结合后,产生了阳离子催化剂体系,该体系引发了1,3-共轭二烯具有高活性的cis-1,4-聚合反应。尤其是,系统1 / [Ph_3C] [B(C _6F_5)_4]在较宽的聚合温度范围(0-80°C)下显示出极好的顺1,4-选择性(> 99%)和活性模式。值得注意的是,活泼的钇-聚二烯活性物种可以进一步引发ε-己内酯的开环聚合反应,从而选择性地制得分子量可控制的聚(顺-1,4-二烯)-b-聚己内酯嵌段共聚物(Mn =(10- 70)-104)和窄的多分散性(PDI = 1.15-1.47)。

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