This review presents the applications of first-row late transition-metal sandwich complexes, including derivatives of ferrocene, FeCp2 (Cp = η5-C5H5), and of salts of cobalticenium [CoCp2]+ and mixed sandwich complexes [FeCp(η6-arene)]+ as molecular or macromolecular electron reservoirs. Forty-five years ago, the concept of electron reservoirs was proposed for the permethylated 19-electron d7 Fe(I) sandwich complexes, in particular [FeCp(η6-C6Me6)] and [FeCp*(η6-C6Me6)] (Cp* = C5Me5), because they were the electron richest neutral molecules known, given their extremely low ionization potentials, and their ability to stoichiometrically or catalytically transfer one electron to a variety of organic and inorganic substrates. These processes occurred without any breakdown of their molecular structure, so that the cationic 18-electron d6 structure was easily recovered. Thus, in this concept, the robustness of both redox forms of the electron-reservoir redox couple is essential. Later, the concept was extended to isolobal sandwich molecules with various numbers of methyl substituents on the ligands in both the [CoCp2]+ and [FeCp(η6-arene)]+ salts in order to cover a wide range of redox potentials. It was also extended to electron hole reservoirs with the 17-electron d5 cations FeCp2+, FeCp*2+ and [FeCp*(η5-C6Me6)]2+. Along the time, the structural flexibility of these Fe and Co sandwich complexes, bringing about modulation of the redox potentials of the redox systems, enriched the concept and its applications. The latter are summarized here including examples of stoichiometric reactions with monometallic complexes and dendritic metalla-macromolecules, redox-flow metallocene batteries and redox sensing. Catalytic applications include redox catalysis, electrocatalysis, i.e. electron-transfer-chain (ETC) catalysis, and Fenton reaction in nanomedicine of ferrocenes, ferrocene dendrimers and metal-organic-framework (MOF)-ferrocenes, utilized in particular as ferroptosis media. Concluding remarks outline key aspects of applications and offer perspectives.

中文翻译：

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二茂铁和其他晚期过渡金属夹心配合物的电子储层应用：液流电池、传感、催化和生物医学


本文介绍了第一行晚期过渡金属夹心配合物的应用，包括二茂铁衍生物 FeCp2 （Cp = η5-C5H5），以及钴盐 [CoCp2]+ 和混合夹心配合物 [FeCp（η6-arene）]+ 作为分子或大分子电子储层。45 年前，针对全甲基化 19 电子 d7 Fe（I） 三明治配合物，特别是 [FeCp（η6-C6Me6）] 和 [FeCp*（η6-C6Me6）] （Cp* = C5Me5），因为它们是已知的电子最丰富的中性分子，因为它们具有极低的电离电位，并且能够化学计量或催化地将一个电子转移到各种有机和无机底物上。这些过程的发生没有破坏它们的分子结构，因此阳离子 18 电子 d6 结构很容易恢复。因此，在这个概念中，电子-储层氧化还原对的两种氧化还原形式的稳健性至关重要。后来，这个概念被扩展到 [CoCp2] + 和 [FeCp（η6-arene）]+ 盐中的配体上具有不同数量甲基取代基的等叶夹心分子，以覆盖广泛的氧化还原电位。它还被扩展到具有 17 电子 d5 阳离子 FeCp2+、FeCp*2+ 和 [FeCp*（η5-C6Me6）]2+ 的电子空穴储层。随着时间的推移，这些 Fe 和 Co 夹心配合物的结构灵活性，带来了对氧化还原系统的氧化还原电位的调制，丰富了这一概念及其应用。这里总结了后者，包括与单金属配合物和树突状金属大分子、氧化还原流偏金属电池和氧化还原传感的化学计量反应的例子。催化应用包括氧化还原催化、电催化，即 电子转移链 （ETC） 催化，以及二茂铁纳米医学中的芬顿反应，二茂铁树状聚合物和金属有机框架 （MOF）-二茂铁，特别是用作铁死亡介质。结束语概述了应用程序的关键方面并提供了观点。