In a first, US team captures plutonium atom in tiny molecular 'cage'

Researchers from Lawrence Livermore National Laboratory, Sandia National Laboratories, and Oregon State University have, for the first time, successfully trapped a plutonium atom inside a Keggin ion, a type of polyoxometalate (POM) molecular cage. Plutonium, a radioactive element with nearly 20 isotopes and diverse applications from nuclear energy to space exploration, forms various coordination compounds, but very few involving POMs had been isolated until now. The team used a specially prepared solution containing just six micrograms of plutonium and bound the metal ion between two negatively charged Keggin ions, which are clusters made of tungsten, oxygen, and a central phosphorus atom. Advanced analytical techniques such as X-ray crystallography, optical spectroscopy, nuclear magnetic resonance, and X-ray scattering confirmed the stability and detailed structure of this new plutonium-POM complex. Notably, unlike similar complexes with metals like cerium, hafnium, and thorium where metal ions align parallel, plutonium