Highly Cis-1,4-Selective Living Polymerization of 1,3-Conjugated Dienes and Copolymerization with 蔚-Caprolactone by Bis(phosphino)carbazolide Rare-Earth-Metal Complexes

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• 作者：Lingfang Wang ; Dongmei Cui ; Zhaomin Hou ; Wei Li ; Yang Li
• 刊名：Organometallics
• 出版年：2011
• 出版时间：February 28, 2011
• 年：2011
• 卷：30
• 期：4
• 页码：760-767
• 全文大小：903K
• 年卷期：v.30,no.4(February 28, 2011)
• ISSN：1520-6041

文摘

Bis(phosphino)carbazole, HL (HL = 3,6-(tBu)₂-1,8-(PPh₂)₂-carbazole), reacted with rare-earth-metal tris(aminobenzyl) complexes (Ln(CH₂C₆H₄N(Me)₂-o)₃) to afford the first PNP-carbazolide rare-earth-metal bis(alkyl) complexes, LLn(C₆H₄CH₂N(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 Y³⁺ ion in a 魏P:魏N:魏P鈥?tridentate mode and the two aminobenzyl groups coordinate to the Y³⁺ ion in 畏¹C:魏N-bidentate modes. Complexes 1鈭?b>3 combined with [Ph₃C][B(C₆F₅)₄] gave cationic catalyst systems that initiated cis-1,4-polymerizations of 1,3-conjugated dienes with high activities. Especially, the system 1/[Ph₃C][B(C₆F₅)₄] displayed excellent cis-1,4-selectivity (>99%) and living mode at a broad range of polymerization temperatures (0鈭?0 掳C). Remarkably, the living yttrium鈭抪olydiene active species could further initiate the ring-opening polymerization of 蔚-caprolactone to give selectively poly(cis-1,4-diene)-b-polycaprolactone block copolymer with controllable molecular weight (M_n = (10鈭?0) 脳 10⁴) and narrow polydispersity (PDI = 1.15鈭?.47).