轴联阻碍合成化合物I模拟的质子-合电子转移反应
Jithin Thomas1, Thirakorn Mokkawes2, Laura Senft3
1Department of Chemistry, The Johns Hopkins University, 3400 North Charles Street, Baltimore, Maryland 21218, United States.
Journal of the American Chemical Society
|April 26, 2024
概括
将轴联体添加到高价值铁氧复合体中显著降低了它们的质子合电子转移 (PCET) 反应性. 这项研究揭示了非贝尔-埃文斯-波兰尼趋势,表明了协同的质子电子转移 (CPET) 机制.
科学领域:
- 生物有机化学
- 有机金属化学
- 催化剂
背景情况:
- 在生物氧化反应中,高价值的铁氧介质至关重要.
- 了解轴联体对反应性的影响是设计合成催化剂的关键.
- 质子合电子转移 (PCET) 是这些系统的一个基本过程.
研究的目的:
- 合成和表征新的6坐标铁 (IV) - 氧基基复合物.
- 研究轴联体对这些铁复合物的PCET反应性的影响.
- 在这些高价值铁氧物种中阐明PCET的机制.
主要方法:
- 使用UV-vis,EPR,Mössbauer光谱和CSI-MS合成和表征铁氧体复合物.
- 使用4-OMe-TEMPOH作为基质的PCET反应的动力学研究.
- 使用密度函数理论 (DFT) 进行计算分析以了解反应性趋势和机制.
主要成果:
- 成功生成和表征了三种具有不同轴联体 (1-MeIm,DMAP,CN-) 的新的6坐标铁-氧复合体.
- 与5个坐标类型相比,第六个轴联体的协调使PCET的反应性降低了多达7000倍.
- 反应性趋势与热力学驱动力或OH键强度无关,而是与还原潜力和电子亲和力相关.
结论:
- 轴联体在调节高价铁氧复合物的PCET反应性方面发挥着至关重要的作用.
- 观察到的反应性趋势表明非贝尔-埃文斯-波兰尼行为,偏离了简单的热力学预测.
- 提出了一种协同的质子电子转移 (CPET) 机制,在过渡状态下进行异步电子/质子运动.
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