Remote Ligand Modifications Tune Electronic Distribution and Reactivity in Site-Differentiated, High-Spin Iron Clusters: Flipping Scaling Relationships
Remote Ligand Modifications Tune Electronic Distribution and Reactivity in Site-Differentiated, High-Spin Iron Clusters: Flipping Scaling Relationships
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DOI：
10.1021/acs.inorgchem.9b02470
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发表时间：
2019-12-02
影响因子：
4.6
通讯作者：
Agapie, Theodor
中科院分区：
文献类型：
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作者：
Arnett, Charles H.;Kaiser, Jens T.;Agapie, Theodor
我们报道了[LFe_3O（（R）ArIm）（3）Fe][OTf]（2）的合成、表征和反应性，这是位点分化簇合物的第一个Hammett系列。团簇还原电位和CO伸缩频率的移动，如预期的基础上的配体的电子性质：给电子的取代基导致更多的还原团簇和较弱的C-O键。然而，观察到不寻常的趋势，其两个连续的CO结合事件的取代基（西格玛）p参数的能量。具体而言，引入给电子取代基抑制第一CO结合事件（Δ Δ H高达7.9 kcal mol（-1）），但增强第二CO结合事件（Δ Δ H高达1.9 kcal mol（-1））。X射线晶体学，包括多波长异常衍射，穆斯堡尔谱，和SQUID磁力，揭示了这些取代基的影响，导致与电子重新分配的集群，这发生在CO结合事件的能量惩罚的变化。
We report the synthesis, characterization, and reactivity of [LFe3O((R)ArIm)(3)Fe][OTf](2), the first Hammett series of a site-differentiated cluster. The cluster reduction potentials and CO stretching frequencies shift as expected on the basis of the electronic properties of the ligand: electron-donating substituents result in more reducing clusters and weaker C-O bonds. However, unusual trends in the energetics of their two sequential CO binding events with the substituent (sigma)p parameters are observed. Specifically, introduction of electron donating substituents suppresses the first CO binding event (Delta Delta H by as much as 7.9 kcal mol(-1)) but enhances the second (Delta Delta H by as much as 1.9 kcal mol(-1)). X-ray crystallography, including multiple-wavelength anomalous diffraction, Mossbauer spectroscopy, and SQUID magnetometry, reveal that these substituent effects result from changes in the energetic penalty associated with electronic redistribution within the cluster, which occurs during the CO binding event.