Nanosized oxide and hydroxide clusters of actinides (uranium, plutonium) play an important role in technology for the nuclear industry, in the migration of the actinides released in the environment by mining, energy production or weapons, and into related remediation strategies. Nanoparticle formation is likely to impact uranium mobility and limit the efficiency of microbial reduction in actinide immobilization.

The paper presents a reproducible method for the synthesis of such clusters from the stoichiometric hydrolysis of low-valent uranium in non-aqueous media. The cluster size can be tuned by the choice of solvent and organic base, leading for instance to a U₁₆ compound that is the largest U^IV cluster reported to date. These new clusters show unprecedented {U₁₀O₁₄} and {U₁₆O₂₄} topologies. These nanosized oxides provide useful models for understanding the chemistry of bulk oxides or colloids.