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论文类型：期刊论文

发表时间：2011-02-28

发表刊物：ORGANOMETALLICS

收录刊物：SCIE、EI

卷号：30

期号：4

页面范围：757-767

ISSN号：0276-7333

摘要：molecular weight (M-n = (10-70) x 10(4)) and narrow polydispersity (PDI = 1.15-1.47).Bis(phosphino)carbazole, HL (HL = 3,6-(tBu)(2)-1,8-(PPh2)(2)-carbazole), reacted with rare-earthmetal 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+ in a kappa P:kappa N:kappa P'-tridentate mode and the two aminobenzyl groups coordinate to the Y3+ ion in eta C-1:kappa N-bidentate modes. Complexes 1-3 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 (0-80 degrees C). Remarkably, the living yttrium polydiene active species could further initiate the ring-opening polymerization of epsilon-caprolactone to give selectively poly(cis-1,4-diene)b-polycaprolactone block copolymer with controllable