Synthesis of Non-Aqueous Neptunium(III) Halide Solvates from NpO2

Two Np(III) halides, NpI₃(THF)₄ and NpBr₃(THF)₄, have been prepared and isolated in high yields as described in this work. Starting with neptunia (NpO₂), NpCl₄(DME)₂ was first generated in an updated, higher yielding synthesis than what was previously reported by using HCl/HF. This material was then reduced with KC₈, followed by subsequent ligand exchange, to generate NpBr₃(THF)₄ and NpI₃-(THF)₄. Full characterization by single-crystal X-ray crystallography, ¹H NMR spectroscopy and electronic absorption spectroscopy confirmed the molecular formulas and oxidation states. These trivalent materials are straightforward to synthesize and can be used as starting materials for non-aqueous Np(III) chemistry, obviating the need for rare and restricted Np metal and elemental halogens.