Unprecedented reduction of the uranyl ion [UO2](2+) into a polyoxo uranium(IV) cluster: Synthesis and crystal structure of the first f-element oxide with a M-6(mu(3)-O)(8) core

The smooth comproportionation reaction of the U( VI) and U( III) complexes UO2(OTf)(2) and U(OTf)(3), afforded the hexanuclear U( IV) oxide cluster [U-6(mu(3)-O)8(mu(2)-OTf)(8)( py) 8], a rare example of a metal oxide with a M-6(mu(3)-O)(8) core.