溶液结构和Hf-Al和Hf-Zn异构金属吸附物的动力学模拟链转移反应中的相关中间体
Leonardo Tensi1, Francesca Moretti2, Alessandra Amendola2
1Department of Pharmaceutical Sciences, University of Perugia and CIRCC, Via del Liceo 1, 06123 Perugia, Italy.
Inorganic chemistry
|April 26, 2024
概括
聚合物中所扮演的角色进行了合成和研究. 一个β-甲基组的方向会影响与链转移剂的反应性,影响聚合动力学.
科学领域:
- 有机金属化学 有机金属化学
- 聚合物化学 聚合物化学
- 催化剂是一种催化剂.
背景情况:
- 阴离子循环金属化哈夫诺是聚合过程中的关键中间体.
- 了解它们的结构-活性关系对于控制聚合过程至关重要.
- 链传递剂 (CTA) 在协调链传递聚合 (CCTP) 和链穿聚合 (CSP) 中发挥着至关重要的作用.
研究的目的:
- 为了合成和表征阴离子环金属化哈夫诺.
- 为了研究最后插入的氨酸性质对异金属复合物的结构,稳定性和反应性的影响.
- 通过研究与CTAs形成的中间体,阐明CCTP和CSP的机制.
主要方法:
- 通过C-H激活合成阴离子环金属化哈夫诺.
- 使用核磁共振 (NMR) 光谱和密度功能理论 (DFT) 计算进行了表征.
- 热力学和动力学研究异金属添加物形成和与CTA反应.
- 拦截和表征反应产品与二氧化化 (DiBAlH).
主要成果:
- 在合成的异构桥梁复合体之间没有观察到任何显著的结构差异,所有这些复合体都表现出多个α-毒性相互作用.
- 只有同位素4a,其β-甲基基向远离 hafnium 中心,与CTAs反应,表明对反应性的立体化学控制.
- 发现异金属添加物的形成是限制速度的步骤,最后插入的α-olefin单元的性质调节了转化动力学.
- 新的异构核和异构三核物种,作为CCTP和CSP中间体的结构模型,被成功拦截和表征.
结论:
- 最后插入的olefin的立体化学显著影响了聚合过程中阴离子环金属化 hafnocenes 的反应性.
- 在CCTP和CSP中,异金属中间体的形成至关重要,其结构和稳定性决定了聚合结果.
- 这项研究为先进的聚合技术的机械路径提供了宝贵的见解,使得可以更好地控制聚合物结构和特性.
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