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.