Np(V) cation-cation interactions. A new contribution from EXAFS spectroscopy?

Actinide cation-cation complexes in aqueous solution have long been a subject of interest. Since the former work of Sullivan et al., several complexes of this type have been discovered, all of them involving an actinide(V) oxocation and either another actinide oxocation or a transition metal cation. Although many studies have been devoted to the structure analysis of such complexes, they have been lacking evidences for the definition of a structural model. In this report. EXAFS spectroscopy has been tentatively used, considering two possible interaction modes: bridging or linear Np-Np interaction.