A Mixed-Valent Uranium Phosphonate Framework Containing U(IV), U(V), and U(VI)

In this work, we showed that UVO2+ ions can reside at UVIO22+ lattice sites during mild reduction and crystallization process under solvothermal conditions, yielding a complicated and rare mixed-valent uranium phosphonate compound that simultaneously contains U(IV), U(V), and U(VI). The presence of uranium with three oxidation states was confirmed by various characterization techniques including X-ray crystallography, X-ray photoelectron, electron paramagnetic resonance, Fourier transform infrared, UV-vis-NIR absorption, magnetism measurements, and synchrotron radiation X-ray absorption spectroscopy.