Time-Resolved X‑ray Scattering and Raman Spectroscopic Studies of Formation of a Uranium-Vanadium-Phosphorus-Peroxide Cage Cluster

Combining reactants
in water under ambient conditions results in the assembly and crystallization
of 2.6 nm diameter cage clusters designated U48V6P48 within 3 weeks. These consist of 24 uranyl hexagonal
bipyramids, 24 uranyl pentagonal bipyramids, six vanadyl square pyramids,
and 48 phosphate tetrahedra. Peroxide-bridged dimers of uranyl hexagonal
bipyramids are linked directly to vanadyl-stabilized tetramers of
uranyl pentagonal bipyramids to form the cage, with phosphate tetrahedra
providing additional linkages between these two units. Time-resolved
small-angle X-ray scattering and Raman spectroscopy indicate that
the combination of the reactants initially resulted in simultaneous
formation of smaller uranyl peroxide cages and vanadyl peroxide complexes.
The disappearance of the smaller uranyl peroxide cages from solution
coincides with the diminution of uncoordinated peroxide, both of which
occurred before the assembly of the relatively peroxide-poor U48V6P48, which clearly occurred in solution
prior to its crystallization.