Hybrid C3-symmetric Tris-phosphane Ligands with Redox-switchable Backbone

即使在今天，在卡宾配体和有机催化的时代，基于二茂铁的膦配体仍然是均相催化过程中不可或缺的组成部分。二茂铁基的构象灵活性、简单的合成可修饰性，特别是对于平面-手性配体，通过定向的1，2-和1，3-二取代，以及二茂铁基的可逆氧化还原活性，导致了二茂铁基配体的不断发展和催化应用。近年来，氧化还原可切换催化受到了特别的重视，除了各种切换状态的正交活性外，它还可以通过改变催化活性中心的性质来实现均相催化剂的循环使用。除了均相催化作用外，含二茂铁基膦配体的过渡金属配合物也是研究的对象，例如用于构建发光材料的超分子金属大环或用于分子电子学。本项目旨在全面探索一类新型的潜在半稳定的异位C3对称的三膦烷配体，该配体基于模块的三(二茂铁基)芳烃核，在2，4，6-位上具有O-和N-给体取代基。除了合成和完全表征外，工作的重点是对配体的电化学理解以及它们对各种过渡金属离子(硬币金属(I)、钯(II)和Ru(II))的配位方式的研究。配体的配位行为在两个方面特别令人感兴趣：虽然杂化设计允许不同的、潜在的半可配位模式，但通过二茂铁基的逐步氧化来影响给体性质的能力也打开了多种可能性。因此，潜在的半稳定的C3对称的三膦配体对所选择的过渡金属离子的配位行为也被明确地从潜在的应用方面进行了探索。除了在(可切换的)催化中使用络合物外，对给体性质以及可能的半稳定行为和氧化还原性质的基本了解也对材料科学的应用感兴趣。

Even today, in the age of carbene ligands and organocatalysis, phosphane ligands based on ferrocene are an indispensable component of homogeneously catalysed processes. The conformational flexibility, the simple synthetic modifiability, especially with respect to planar-chiral ligands, through targeted 1,2- and 1,3-disubstitution, as well as the reversible redox activity of the ferrocenyl group have led to the continuous development and catalytic application of ferrocene-based ligands. In recent years, particular emphasis has been placed on redox-switchable catalysis, which, in addition to orthogonal activities of the various switching states, can also enable the recycling of homogeneous catalysts through altered properties of the catalytically active centres. In addition to homogeneous catalysis, transition-metal complexes containing ferrocenylphosphane ligands are also the subject of research, for example, in the construction of supramolecular metallamacrocycles for luminescent materials or for use in molecular electronics.This project aims to comprehensively explore a novel class of potentially hemilabile heteroditopic C3-symmetric tris-phosphane ligands based on a modular tris(ferrocenyl)arene core with O- and N-donor substituents in 2,4,6-position. In addition to the synthesis and full characterisation, the focus of the work is, in particular, the electrochemical understanding of the ligands as well as the investigation of their coordination modes towards various transition metal ions (coinage metals(I), palladium(II), and ruthenium(II)). The coordination behaviour of the ligands is of particular interest in two respects: while the heteroditic design allows for different, potentially hemilabile coordination modes, the ability to influence the donor properties by stepwise oxidation of the ferrocenyl groups also opens up manifold possibilities. Therefore, the coordination behaviour of the potentially hemilabile heteroditopic C3-symmetric tris-phosphane ligands towards selected transition-metal ions is also explicitly explored with respect to prospective applications. In addition to the use of complexes in (switchable) catalysis, the basic understanding of donor properties and possibly hemilabile behaviour and redox properties is also of interest for applications in materials science.