A Mixed-Valent Uranium Phosphonate Framework Containing UIV, UV, and UVI

It is shown 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 UIV, UV, and UVI. The presence of uranium with three oxidation states was confirmed by various characterization techniques, including X‐ray crystallography, X‐ray photoelectron, electron paramagnetic resonance, FTIR, UV/Vis‐NIR absorption, and synchrotron radiation X‐ray absorption spectroscopy, and magnetism measurements. Three's company: A complex uranium compound was synthesized by a redox‐active solvothermal reaction. It is the first phosphonate compound that contains three oxidation states of uranium simultaneously.