Neptunium chloro-complexes

Abstract

The yellow anhydrous neptunium(V) chloro-complexes, M₂NpOCl₅(M = Cs⁺ or Ph₄As⁺), turquoise Cs₃NpO₂Cl₄, and the dark yellow neptunium(VI) complex, Cs₂NpO₂Cl₄, have been prepared from aqueous hydrochloric acid. Neptunium pentoxide and neptunium(V) hydroxide are chlorinated by acetyl chloride and thionyl chloride, but disproportionation occurs with the former, and reduction to neptunium(IV) with the latter. The attempted preparation of hexachloroneptunates(V) was also unsuccessful. X-Ray diffraction, infrared spectra, and magnetic susceptibility results are reported for the oxychloro-complexes, for Cs₂NpCl₆, and for the NN-dimethylacetamide (DMA) complex, NpCl₄,2·5DMA.