Exploring the mechanism of Grignard metathesis polymerization of 3-alkylthiophenes.
Exploring the mechanism of Grignard metathesis polymerization of 3-alkylthiophenes.
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探索3-烷基噻吩的格氏复分解聚合机理。
DOI：
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发表时间：
2014
影响因子：
4
通讯作者：
Seyed Amin Mirmohammadi
中科院分区：
文献类型：
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作者：
Naeimeh Bahri‐Laleh;A. Poater;L. Cavallo;Seyed Amin Mirmohammadi
在这项研究中，我们已经通过GRIM方法计算研究了2，5-二溴-3-丁基噻吩的聚合机理，重点是头-尾（HT）选择性的起源。为此，首先将格氏试剂氧化加成到单体上，得到2-溴-5-氯镁-3-丁基噻吩（中间体I1）或2-氯镁-5-溴-3-丁基噻吩（中间体I2）区域异构体。然后使用常用的Ni（dppp）Cl 2 [dppp：1，3-双（二苯基膦基）丙烷]和Pd（dppp）Cl 2催化剂将中间体I1和I2催化聚合成一系列区域特异性聚-3-丁基噻吩。由于作为活性单体物质的I1和I2的不对称性质，可能发生6种偶联模式。所有模式的整体能量分布已被研究，通过考虑一个三阶段的机制，包括协调，transmetalation，和还原消除，定量比较所谓的催化剂的能力，在选择性偶联所需的异构体，以产生regioregular聚-3-丁基噻吩。最后，为了量化dppp在区域选择性中的空间作用，进行了空间图方面的掩埋体积的分析。
In this study we have investigated computationally the mechanism of polymerization of 2,5-dibromo 3-butylthiophene via the GRIM method, with the focus on the origin of the head to tail (HT) selectivity. To this end, first the Grignard reagent underwent oxidative addition to the monomer to afford the 2-bromo-5-chloromagnesio-3-butylthiophene (intermediate I1) or the 2-chloromagnesio 5-bromo-3-butylthiophene (intermediate I2) regioisomers. Then intermediates I1 and I2 were polymerized catalytically to a series of regiospecific poly-3-butylthiophenes using the commonly used Ni(dppp)Cl2 [dppp: 1,3-bis(diphenylphosphino) propane] and Pd(dppp)Cl2 catalysts. Due to the asymmetric nature of I1 and I2 that act as the active monomeric species, 6 coupling modes may occur. The whole energy profile of all modes has been studied by considering a three-stage mechanism, including coordination, transmetalation, and reductive elimination, to compare quantitatively the ability of so-called catalysts in selective coupling of desired isomers to produce regioregular poly-3-butylthiophene. Finally, to quantify the steric role of the dppp in regioselectivity, analysis of the buried volume in terms of steric maps was performed.