First observation of [Pu6(OH)4O4]12+ cluster during the hydrolytic formation of PuO2 nanoparticles using H/D kinetic isotope effect.

New insights are provided about the formation mechanism of PuO2 nanoparticles (NPs) by investigating an unprecedented kinetic isotope effect observed during their hydrolytic synthesis in H2O or D2O and attributed to OH/OD zero point energy difference. The signature of a Pu(IV) oxo-hydroxo hexanuclear cluster, appearing as an important intermediate during the formation of the 2 nm PuO2 NPs (synchrotron SAXS/XAS), is further revealed indicating that their formation is controlled by H-transfer reactions occurring during hydroxo to oxo-bridge conversions.