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-Bu-t(2) 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 K(2)salfen. 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.