Isolation of an Americium Complex Containing a Radical Ligand

The synthesis, characterization, and electronic structure of Cp*2Am­(tBu2bipy•–) (1-Am) (Cp* = pentamethylcyclopentadienide; tBu2bipy = 4,4′-di-tert-butyl-2,2′-bipyridine), the first isolated and structurally verified americium complex containing a radical ligand, is reported. Theoretical calculations (DFT and multiconfigurational methods) alongside experimental comparisons of M–N distances reveal a greater degree of metal–ligand covalency in 1-Am compared to near-isoradial lanthanide counterparts 1-Nd and 1-Sm. Electrochemical studies suggest that 1-Am may behave as an “Am­(II) synthon”, and a preliminary attempt to probe the chemical reactivity of 1-Am is briefly discussed.