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, ¹ H 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.