Synthesis and spectroscopy of new plutonium(III) and -(IV) molybdates: Comparisons of electronic characteristics

Synthesis of a plutonium(III) molybdate bromide, PuMoO₄Br(H ₂O), has been accomplished using hydrothermal techniques in an inert-atmosphere glovebox. The compound is green in color, which is in stark contrast to the typical blue color of plutonium(III) complexes. The unusual color arises from the broad charge transfer (CT) spanning from approximately 300 to 500 nm in the UV-vis-near-IR spectra. Repeating the synthesis with an increase in the reaction temperature results in the formation of a plutonium(IV) molybdate, Pu₃Mo₆O₂₄(H₂O) ₂, which also has a broad CT band and red-shifted f-f transitions. Performing an analogous reaction with neodymium produced a completely different product, [Nd(H₂O)₃][NdMo₁₂O₄₂] ·2H₂O, which is built of Silverton-type polyoxometallate clusters.