Synthesis, Electrochemistry, and Optical Properties of Highly Conjugated Alkynyl-Ferrocenes and -Biferrocenes
Synthesis, Electrochemistry, and Optical Properties of Highly Conjugated Alkynyl-Ferrocenes and -Biferrocenes
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DOI：
10.1021/acs.organomet.1c00098
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发表时间：
2021-04-12
期刊：
影响因子：
2.8
通讯作者：
Long, Nicholas J.
中科院分区：
文献类型：
--
作者：
Bennett, Troy L. R.;Wilkinson, Luke A.;Long, Nicholas J.
Sonogashira反应在本文中用于使碘代二茂铁和-双二茂铁与末端炔配体反应，末端炔配体用吡啶和苯硫醚基团两者官能化。高产率反应产生单炔基和二炔基衍生物，其比例可以通过反应化学计量的变化来改变。这种方法使我们能够合成一个大家族的衍生物，包括四个对称的衍生物（3xx，其中x表示苯基取代的末端炔）和六种较少研究的不对称衍生物（3xy，其中x和y表示两个不同的苯基取代的末端炔），以及许多它们的双二茂铁基类似物（6x，7 xx和7 xy），包括不对称双取代的双二茂铁的第一个已知实例。我们研究了所有系统在溶液中的电化学行为，通过使用循环伏安法，并证明这些高度共轭的炔基配体施加微妙的氧化还原控制中心二茂铁基序。我们还注意到，这些取代基显示一些控制的混合价字符存在于biferrocene单价，与苯甲醚硫代取代基赋予几乎一个数量级更高的K-C比他们的吡啶类似物，和不对称系统显示罕见的混合价异构体的特性。这些系统的电子结构进一步阐明通过结合紫外/维斯光谱和密度泛函理论计算。我们的方法提供了一个简便和适应性强的路线走向隔离的一些新的二茂铁和双二茂铁衍生物。从我们的角度来看，这些系统的不对称性质，沿着这些配体对中心二茂铁单元施加的微妙和可预测的氧化还原控制，可能导致在分子电子学中的应用，其中这些性质先前在二极管和整流器的制造中以及在供体-π-受体系统的合成中显示出希望。
Sonogashira reactions are utilized herein to react iodoferrocenes and -biferrocenes with terminal alkyne ligands, functionalized with both pyridine and thioanisole groups. High-yielding reactions generate both monoalkynyl and dialkynyl derivatives, the ratio of which can be altered through changes in the reaction stoichiometry. This methodology allowed us to synthesize a large family of derivatives, comprising four symmetrical derivatives (3xx, where x represents a phenylsubstituted terminal alkyne) and six less-studied asymmetrical derivatives (3xy, where x and y represent two different phenyl-substituted terminal alkynes), as well as a number of their biferrocenyl analogues (6x, 7xx, and 7xy), including the first known examples of asymmetrically disubstituted biferrocenes. We examined the electrochemical behavior of all the systems in solution through the use of cyclic voltammetry and demonstrate that these highly conjugated alkynyl ligands exert delicate redox control over the central ferrocene motif. We also note that these substituents display some control over the mixed-valence character present in biferrocene monocations, with thioanisole substituents imparting almost an order of magnitude higher K-c than their pyridyl analogues, and asymmetric systems displaying rare characteristic properties of mixed-valence isomers. The electronic structure of these systems was further elucidated through a combination of UV/vis spectroscopy and density functional theory calculations. Our methodology provides a facile and adaptable route toward the isolation of a number of novel ferrocene and biferrocene derivatives. From our perspective, the asymmetric nature of these systems, along with the delicate and predictable redox control that these ligands exert on the central ferrocene unit(s), could lead to applications in molecular electronics, where these properties have previously shown promise in the fabrication of diodes and rectifiers, as well as in the synthesis of donor-pi-acceptor systems.