Expansion of the Na3MIII(Ln/An)6F30 Series: Incorporation of Plutonium into a Highly Robust and Stable Framework

Na n MAn 6 F 30  is an extremely versatile framework structure for incorporating tetravalent actinides (An) and cerium along with divalent or trivalent  d -metals (M); moreover, the structure exhibits a high resistance to harsh chemical conditions. This extreme robustness can potentially be exploited for the sequestration of Pu in a stable matrix; however, no Na n MPu 6 F 30  compounds have been reported so far. Herein, we present four new plutonium fluorides that have been prepared as single crystals via mild hydrothermal synthesis methods. Structural characterizations revealed their compositions to be Na 3 AlPu 6 F 30 , Na 3 FePu 6 F 30 , Na 3 CoPu 6 F 30 , and Na 2.4 Mn 1.6 Pu 6 F 30 . Surprisingly, in the plutonium series it was found that Co 2+  and Mn 2+  precursors oxidized to form Na 3 Co III Pu 6 F 30  and Na 2.4 Mn II/III 1.6 Pu 6 F 30 , whereas the analogous reactions for cerium result in reduction of the transition metal, even when beginning with a M 3+  precursor. While cerium is often used as a surrogate for plutonium, this work serves as an example that deviations between their chemistries do occur.