在非经典的三角形 (TPB) Co-H2 复合体中,自由 H2 旋转与 Jahn-Teller 约束相比
William A Gunderson1, Daniel L M Suess, Henry Fong
1Department of Chemistry, Northwestern University , Evanston, Illinois 60208-3113, United States.
Journal of the American Chemical Society
|September 23, 2014
概括
在化复合体中,质子交换是通过旋转发生的,与显示局部化的铁复合体不同. 这种差异是由于不同的电子结构和振动合影响分子对称性和旋转障碍.
科学领域:
- 无机化学 无机化学
- 量子化学 是一个量子化学.
- 频谱学是一种光谱学.
背景情况:
- 金属化物复合体中的质子交换对于理解化学反应性至关重要.
- 雅恩-泰勒 (JT) 活性状态和振动合显著影响分子行为.
- 通过比较 (Co-H2) 和铁 (Fe-H2) 化物复合物,可以了解电子结构效应.
研究的目的:
- 通过旋转研究 (TPB) Co(H2) (Co-H2) 中的质子交换机制.
- 为了比较H2在Co-H2中的动态与先前研究的Fe-H2.2.
- 阐明电子结构和振动合在H2动态中的作用.
主要方法:
- 电子偏磁共振 (EPR) 和电子核双共振 (ENDOR) 光谱学.
- 用中子衍射来确定晶体结构.
- 对分子动力学一维旋转机问题的分析.
主要成果:
- 由于C3对称性和H2交换引起的6倍旋转障碍,Co-H2在2K处表现出类似于旋转器的H2行为.
- Fe-H2 显示 H2 在 2 K 的局部化,这是由于 Fe(3d)→H2(σ*) π 背接和二次性 JT 扭曲的占主导地位的双重障碍.
- 恩多尔光谱学揭示了Co-H2和Fe-H2.2的明显的结合特性和超细合.
结论:
- 通过在Co-H2轴周围的旋转,H2在Co-H2中进行质子交换,受量子统计要求的约束.
- 在Co-H2和Fe-H2中不同的旋转障碍是由于电子结构,振动合和分子对称性的变化造成的.
- 这项研究强调了ENDOR光谱在探测化物复合体中的金属-连接体相互作用方面的灵敏度.
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