通过Fe(+) 催化的norbornadiene和norbornene的反循环的密度功能研究
1Department of Chemistry, Auburn University, Auburn, Alabama 36849, USA.
Journal of the American Chemical Society
|September 20, 2001
概括
Fe(+) 催化剂促进了norbornadiene (NBD) 和norbornene (NBN) 的反复Diels-Alder反应,降低了激活障碍. 本研究详细介绍了这些有机金属复合物的反应途径和中间体.
科学领域:
- 有机金属化学 有机金属化学
- 计算化学的计算化学
- 反应机制 反应机制
背景情况:
- 反复的迪尔斯-阿尔德反应是一种基本的有机转化.
- 已知铁催化剂会影响反应通路和动力学.
- 了解反应机制对于催化剂设计和合成应用至关重要.
研究的目的:
- 研究Fe(+) 对norbornadiene (NBD) 和norbornene (NBN) 的反复Diels-Alder反应的催化作用.
- 阐明反应机制,包括逐步与协调的途径和中间形成.
- 为了比较相关的铁碳复合物的电子特性和反应性.
主要方法:
- 用密度函数理论 (DFT) 的计算来建模反应路径.
- 确定了催化和未催化反应的激活障碍和过渡状态.
- 分析了潜在能量表面,以确定低能反应通道和中间体.
主要成果:
- 与协调的路径相比,Fe(+) 催化剂将NBD的逐步逆向Diels-Alder的激活障碍降低3.1 kcal/mol.
- 对于NBN,Fe(+) 催化阶段反应的阻力比未催化阶段反应低,但高于协调路径.
- 关键的中间体,C(5) H(6) FeC(2) H(2) +) 和C(5) H(6) FeC(2) H(4) +),经过轻松的转移,形成稳定的环二烯-铁复合体.
- 对于NBD和NBN中间体的最低能量路径涉及单个四重复数.
结论:
- Fe(+) 显著改变了NBD和NBN的Diels-Alder反向反应机制,在某些条件下有利于循序渐进的路径.
- 该研究提供了铁在通过特定中间体调解这些转变中的作用的见解.
- 将C(2) H(2) 和C(2) H(4) 复合物与CpFe(+) 和C(5) H(6) Fe(+) 复合物进行比较,可以发现它们在电子结构和反应性方面的差异.
相关概念视频
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