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首页> 外文期刊>Chemistry, an Asian journal >Copolymerization of Isoprene and Nonconjugated α,ω-Dienes by Half-Sandwich Scandium Catalysts with and without a Coordinative Side Arm
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Copolymerization of Isoprene and Nonconjugated α,ω-Dienes by Half-Sandwich Scandium Catalysts with and without a Coordinative Side Arm

机译：带有和不带有配位侧臂的半夹心Scan催化剂对异戊二烯和非共轭α，ω-二烯的共聚合

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摘要

A series of half-sandwich scandium-dialkyl complexes that bear various auxiliary ligands have been examined for the copolymerization of isoprene (IP) with nonconjugated α,ω-dienes such as 1,5-hexadiene (HD) and 1,6-heptadiene (HPD). Significant ligand influence on the catalytic activity and selectivity has been observed. The thf-coordinated complex [(C_5Me_4SiMe_3)Sc(CH_2SiMe_3)_2(thf)] (2) and the methoxy side arm containing the half-sandwich complex [(C_5Me_4C_6H_4OMe-o)Sc(CH_2SiMe_3)_2] (3), in combination with an equivalent of [Ph_3C][B(C_6F_5)_4], can serve as excellent catalysts for the random cycloco-polymerizations of IP with HD and HPD. The resulting random HD-IP copolymers contain five-membered-ring methylene-1,3-cyclopentane (MCP), 3,4-polyisoprene (3,4-IP), and 1,4-polyisoprene (1,4-IP) units with controllable HD incorporation in a range of 17-82mol%. The random HPD-IP copolymers possess six-membered-ring methylene-1,3-cyclohexane (MCH), 1,4-IP, and 3,4-IP units with HPD incorporation in a range of 11-55 mol%. By use of a catalyst that bears a phosphine oxide group [{C_5Me_4SiMe_2CH_2P(O)Ph_2}Sc-(CH_2SiMe_3)_2] (5), the alternating co-polymerizations of IP with HD and HPD have been achieved for the first time in which HD and HPD are completely cyclized to the MCP and MCH units, respectively. More remarkably, in the alternating copolymerization of HPD and IP by 5, the regio- and stereospecific cis-MCH selectivity reached as high as 99%. The microstructures and compositions of these copolymers showed significant influences on their mechanical properties.
机译：对于异戊二烯（IP）与非共轭的α，ω-二烯，例如1,5-己二烯（HD）和1,6-庚二烯（ HPD）。已经观察到配体对催化活性和选择性的显着影响。 thf配位化合物[（C_5Me_4SiMe_3）Sc（CH_2SiMe_3）_2（thf）]（2）和含半三明治复合物[（C_5Me_4C_6H_4OMe-o）Sc（CH_2SiMe_3）_2]（3）的甲氧基侧臂具有[Ph_3C] [B（C_6F_5）_4]的当量，可以用作IP与HD和HPD的无规环聚合的极佳催化剂。所得的无规HD-IP共聚物包含五元环亚甲基-1,3-环戊烷（MCP），3,4-聚异戊二烯（3,4-IP）和1,4-聚异戊二烯（1,4-IP） HD掺入量可控制在17-82mol％范围内的单元。无规HPD-IP共聚物具有六元环亚甲基-1,3-环己烷（MCH），1,4-IP和3,4-IP单元，HPD掺入范围为11-55 mol％。通过使用带有氧化膦基团的催化剂[{C_5Me_4SiMe_2CH_2P（O）Ph_2} Sc-（CH_2SiMe_3）_2]（5），首次实现了IP与HD和HPD的交替共聚，其中HD和HPD分别完全循环到MCP和MCH单元。更为显着的是，在HPD和IP通过5交替共聚时，区域和立体特异性的顺式MCH选择性高达99％。这些共聚物的微观结构和组成对其机械性能显示出重大影响。

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