Programming Palladium Cage Geometry through Ligand Redox Modulation

Abstract

ABSTRACT Incorporating redox active ligands into coordination cages offers a direct way to reach architectures whose structure or composition can be modulated in response to changes in the oxidation state. An exTTF‐based ditopic ligand L affords a M 2 L 4 cage in presence of a palladium(II) salt (M). The resulting M 2 L 4 cavity exhibits selective binding properties for medium length α,ω‐dinitrile alkanes. Modifying the coordination geometry of the ligand by oxidation to its L ox state redirects the self‐assembly process toward a M 2 L ox 2 structure. The oxidized ligand can also be combined with a dibenzothiophene linker (L′) to afford a heteroleptic M 2 L ox L′ 2 structure whose vacant coordination sites enable subsequent dimerization into an unprecedented M 4 L 4 L′ 4 architecture. Key intermediates and products were structurally authenticated by single‐crystal x‐ray diffraction. Notably, these processes are reversible. Reduction converts the M 2 L ox L′ 2 assembly back to the homoleptic M 2 L 4 cage. This sequence illustrates how changes of oxidation state can reshape nuclearity and composition in metal organic assemblies.