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DOE OSTI · 2311306

Structure and bonding of a radium coordination compound in the solid state

White, Frankie D.·Thiele, Nikki A.·Simms, Megan E.·Cary, Samantha K.
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Abstract

The structure and bonding of radium (Ra) is poorly understood because of challenges arising from its scarcity and radioactivity. Here we report the synthesis of a molecular Ra 2+ complex using 226 Ra and the organic ligand dibenzo-30-crown-10, and its characterization in the solid state by single-crystal X-ray diffraction. The crystal structure of the Ra 2+ complex shows an 11-coordinate arrangement comprising the 10 donor O atoms of dibenzo-30-crown-10 and that of a bound water molecule. Under identical crystallization conditions, barium (Ba 2+ ) yielded a 10-coordinate ‘Pac-Man’-shaped structure lacking water. Furthermore, the bond distance between the Ra centre and the O atom of the coordinated water is substantially longer than would be predicted from the ionic radius of Ra 2+ and by analogy with Ba 2+ , supporting greater water lability in Ra 2+ complexes than in their Ba 2+ counterparts. In conclusion, barium often serves as a non-radioactive surrogate for radium, but our findings show that Ra 2+ chemistry cannot always be predicted using Ba 2+ .

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White, Frankie D., Thiele, Nikki A., Simms, Megan E., Cary, Samantha K.. 2023-11-09. Structure and bonding of a radium coordination compound in the solid state. https://doi.org/10.1038/s41557-023-01366-z

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