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

• Applicant: Professorin Dr. Evamarie Hey-Hawkins
• Subject Area: Inorganic Molecular Chemistry - Synthesis and Characterisation
• Term: from 2020 to 2024
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 441499683

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.

• DFG Programme: Research Grants