Swapping O for N

Science  23 Dec 2005:
Vol. 310, Issue 5756, pp. 1865
DOI: 10.1126/science.310.5756.1865l

The uranyl ion, O=U=O2+, despite its abundance, is a rare example of multiple bonding between a light atom and an actinide metal. A fundamental question in the formation of such complexes is the specific role of partially occupied f-orbitals, or electron distributions unique to the lanthanide and actinide elements. Hayton et al. (p. 1941) have prepared two analogs of uranyl, in which the multiply bonded oxygens are replaced by either alkyl or aryl nitrogen groups. These complexes result from an efficient iodine oxidation of uranium metal in the presence of an amine and are shown by x-ray crystallography to resemble uranyl in their trans N=U=N coordination geometries. Density functional theory calculations shed light on the orbitals involved in the bonding, and the comparative electronic structures of the nitrogen and oxygen compounds.

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