Organometallic radicals of iron and ruthenium: Similarities and dissimilarities of radical reactivity and charge delocalization
Organometallic radicals of iron and ruthenium: Similarities and dissimilarities of radical reactivity and charge delocalization
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DOI：
10.1016/j.ccr.2019.02.036
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发表时间：
2019-06
影响因子：
20.6
通讯作者：
Yuya Tanaka;M. Akita
中科院分区：
文献类型：
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作者：
Yuya Tanaka;M. Akita
铁（II）和钌（II）配合物的氧化还原化学已被广泛研究，这是由于单核自由基的有趣反应性和双核混合价（MV）配合物的电荷离域性质。特别是，有机金属双核MV系统表现出远程电荷离域行为，其性质可以通过金属(M)和桥接配体（BL）的选择来改变。本文综述了以CP2M和CPM（dppe）片段为氧化还原中心的单核和双核自由基（CP =η5-C5H5orη5-C5Me5; M = Fe, Ru）。虽然铁和钌经常是同构的，但它们的电子结构却有很大的不同。在Fe和Ru配合物中，自由基中心倾向于定位于金属中心和配体部分。对于单核物质，钌配合物在配体上表现出自由基偶联的反应性，而铁配合物可能保持为单体自由基。对于双核配合物，混合价双铁原子团的原子团中心更倾向于定位在金属原子团中心，而与之类似的二钌原子团的原子团中心则倾向于定位在金属原子团中心。这种差异可归因于电子转移引起的重组，而铁原子团的原子团中心的贡献程度可通过铁原子团的ν最大值与其Ru衍生物（Δνmax(Ru-Fe)）之间的差异来估计。
Redox chemistry ofd6iron(II) and ruthenium(II) complexes has been studied extensively due to the interesting reactivity of mononuclear radical species and the charge-delocalized properties of dinuclear mixed-valence (MV) complexes. In particular, organometallic dinuclear MV systems show long-range charge-delocalized behavior, and their properties can be modified by the choice of the metal (M) and the bridging ligand (BL). Here we review mono- and di-nuclear radical species having CP2M and CPM(dppe) fragments (CP =η5-C5H5orη5-C5Me5; M = Fe, Ru) as the redox centers. Although the Fe and Ru species are frequently isostructural, the electronic structures of them are considerably different. Radical center tends to localize rather on the metal center and the ligand part in the Fe and Ru complexes, respectively. For mononuclear species, the Ru complexes exhibit reactivity at the ligand to undergo radical coupling, whereas the Fe complexes may stay as monomeric radical species. For dinuclear complexes, the radical center of mixed-valence diiron species rather localizes on the metal center, while that of the diruthenium analogues tends to localize on the BL. The difference could be ascribed to reorganization caused by the electron transfer, and the extent of the contribution of the BL-localized state can be estimated by the difference between the νmaxvalues for an Fe complex and its Ru derivative (Δνmax(Ru-Fe)).