In initial attempts to synthesize neptunium (III/IV) halide adducts, several unanticipated neptunium(IV) compounds were isolated. The dissolution and recrystallization of material having the nominal composition of NpCl 4 (DME) 2 from chloroform resulted in the formation of the dimeric species, NpCl 3 (µ‐Cl)(DME) 2 . It was also discovered that hydroxylamine added for the valence adjustment of neptunium remained during reaction workup, forming (NH 3 OH) 2 NpCl 6 •3(dioxane) instead of the desired NpCl 4 (dioxane) x adduct. Lastly, the presence of hydrogen bromide in trimethylsilylbromide resulted in the isolation of H(THF) 2 NpBr 5 THF, rather than NpBr 4 . The synthesis and characterization of these compounds outline guidelines to avoid side products during transuranium halide syntheses. These three novel neptunium halides possess interesting structural features and contribute more knowledge to the growing field of transuranium chemistry.
Whitefoot et al. (Thu,) studied this question.