Organometallic neptunium(III) complexes

Studies of transuranic organometallic complexes provide a 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 the 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. In comparison with lanthanide analogues, significant d- and f-electron contributions to key NpIII orbitals are observed, which shows that fundamental neptunium organometallic chemistry can provide new insights into the behaviour of f-elements

Activation of Small Molecules by U(III) Cyclooctatetraene and Pentalene Complexes

The low-valent complexes of uranium (i.e. those containing U(III) centres) are characterised as reactive, highly reducing species that can effect novel, and potentially useful, transformations of small molecules. In this chapter we review one particular class of these compounds - those supported by cyclooctatetraene and pentalene ligands - whose reduction chemistry has recently demonstrated novel and unexpected results, including the cyclooligomerisation of CO. The syntheses and structures of these compounds are presented, and their reactivity towards a variety of small molecules is examined and reviewed. The reactivity towards carbon monoxide is discussed in reference to the historical development of obtaining oxocarbons from CO