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也是均相催化过程中不可或缺的组成部分。二茂铁基配体的构象灵活性、简单的合成修饰性（特别是通过靶向1，2-和1，3-双取代的平面手性配体）以及可逆的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，特别强调氧化还原可切换催化，其除了各种切换状态的正交活性之外，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再循环。除了均相催化，含有二茂铁基膦配体的过渡金属配合物也是研究的主题，例如，本项目旨在全面探索一类新型的半不稳定的C3-对称三膦配体，它们是基于一个模块化的三膦配体，在2，4，6-位具有O-和N-供体取代基的（二茂铁基）芳烃核。除了合成和充分的表征，工作的重点是，特别是，配体的电化学理解以及对各种过渡金属离子（钴金属（I），钯（II），和钌（II））的配位模式的调查。配体的配位行为在两个方面特别令人感兴趣：虽然杂合设计允许不同的、潜在的半不稳定的配位模式，但通过逐步氧化二茂铁基基团来影响供体性质的能力也开辟了多种可能性。因此，潜在的hemilabile heteroditopic C3-对称的三-膦配体对选定的过渡金属离子的配位行为也明确探讨相对于有前景的应用。除了在（可切换）催化中使用配合物外，对供体性质和可能的半不稳定行为和氧化还原性质的基本理解也对材料科学中的应用感兴趣。

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.