Ferrocene-Based Tetradentate Schiff Bases as Supporting Ligands in Uranium Chemistry

Uranyl­(VI), uranyl­(V), and uranium­(IV) complexes supported by ferrocene-based tetradentate Schiff-base ligands were synthesized, and their solid-state and solution structures were determined. The redox properties of all complexes were investigated by cyclic voltammetry. The bulky salfen-^tBu₂ allows the preparation of a stable uranyl­(V) complex, while a stable U­(IV) bis-ligand complex is obtained from the salt metathesis reaction between [UI₄(OEt₂)₂] and K₂salfen. The reduction of the [U­(salfen)₂] complex leads to an unprecedented intramolecular reductive coupling of the Schiff-base ligand resulting in a C–C bond between the two ferrocene-bound imino groups