First observation of [Pu 6 (OH) 4 O 4 ] 12+ cluster during the hydrolytic formation of PuO 2 nanoparticles using H/D kinetic isotope effect.

New insights are provided about the formation mechanism of PuO 2 nanoparticles (NPs) by investigating an unprecedented kinetic isotope effect observed during their hydrolytic synthesis in H 2 O or D 2 O 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 PuO 2 NPs (synchrotron SAXS/XAS), is further revealed indicating that their formation is controlled by H-transfer reactions occurring during hydroxo to oxo-bridge conversions.