Organometallic neptunium(III) complexes

Studies of transuranic organometallic complexes provide particularly valuable insight into covalent contributions to the metal-ligand bonding, in which the subtle differences between the transuranium actinide ions and their lighter lanthanide counterparts are of fundamental importance for effective remediation of nuclear waste. Unlike the organometallic chemistry of uranium, which has focused strongly on UIII and has seen some spectacular advances, that of the transuranics is significantly technically more challenging and has remained dormant. In the case of neptunium, it is limited mainly to NpIV. Here we report the synthesis of three new NpIII organometallic compounds, and the characterization of their molecular and electronic structures. These studies suggest that NpIII complexes could act as single molecule magnets, and that the lower oxidation state of NpII is chemically accessible. Significant d- and f-electron contributions to key NpIII orbitals are observed, in comparison with lanthanide analogues, showing that fundamental neptunium organometallic chemistry can provide new insight into the behaviour of f-elements.