Insights at the molecular level into the formation of oxo-bridged trinuclear uranyl complexes.

Reaction of 1,3,4,6-tetra- O -acetyl- N -(2-hydroxy)-naphthylidene glucosamine (HL(Ac)) with uranyl acetate in ethanol leads to formation of dinuclear [(UO 2 ) 2 (L) 2 ] (1). In a second step 1 is quantitatively transferred into the trinuclear oxo-bridged complex [(UO 2 ) 3 (μ 3 -O)(L) 3 ] 2- (2 2- ) via deprotonation and coordination of a water molecule. This transformation was followed by NMR and UV/Vis spectroscopy and it proved possible to selectively introduce 18 O into the μ 3 -bridge.