Highly Functionalized Brønsted Acidic/Lewis Basic Hybrid Ferrocene Ligands: Synthesis and Coordination Chemistry

Abstract

A general challenging issue in the synthesis of hemilabile ferrocene ligands is the access to highly functionalized ferrocene starting materials. These can bear donor/acceptor atoms, additional functional and structuring spectator substituents, but the preparation of such species poses general synthetic difficulties. We report herein alternative synthetic routes to hybrid ferrocene donors such as tert‐butylated phosphanylcarboxylic acids and their corresponding aldehydes. These hybrid ambiphilic species that combine Brønsted‐acidic and Lewis‐basic functional moieties in their structure were characterized by multinuclear NMR and single‐crystal X‐ray diffraction analysis. In the solid state, the mutual arrangement of functional groups at the ferrocene unit is highly dependent on hydrogen bonding interactions despite the structural hindering effect of the tert‐butyl groups introduced. The ligands were converted to gold(I) complexes and phosphane selenides to further monitor the properties and mutual influence of the functional groups in the prepared compounds.