The discovery of molecular metal-metal bonds has been of fundamental importance to the understanding of chemical bonding.1 For the actinides, examples of unsupported metalmetal bonds are relatively uncommon, consisting of Cp 3 USnPh 3 , and several actinide-transition metal complexes. Traditionally, bonding in the f-elements has been described as electrostatic; however, elucidating the degree of covalency is a subject of recent research. 3 In carbon monoxide complexes of the trivalent uranium metallocenes, decreased ν CO values relative to free CO suggest that the U(III) atom acts as a π-donor. 4 Ephritikhine and coworkers have demonstrated that π-accepting ligands can differentiate trivalent lanthanide and actinide ions, an effect that renders this chemistry of interest in the context of nuclear waste separation technology.