Hexavalent uranium dicarboxylates with hydrazine. Preparation,characterization and thermal studies

The uranium complexes of composition,UO₂X⋅N₂H₄⋅H₂O, X=succinate or glutarate, UO₂X₂⋅N₂H₄⋅H₂O, X=Hadipate, Hpimelate, Hsuberate, Hazelate and Hsebacate and UO₂X⋅N₂H₄, where X=malate and oxydiacetate have been prepared and characterized by analytical, spectral (IR and electronic), thermal and X-ray powder diffraction studies. Hydrazine acts as a monodentate ligand in uranyl succinate, glutarate, malate and oxydiacetate hydrazinates and bidentate in uranyl adipate, pimelate, suberate, azelate and sebacate hydrazinate hydrate complexes. The dicarboxylate anions bind the uranium through uni- and bidentate fashion depending upon the coordination polyhedra. All the dicarboxylate hydrazinate complexes in this series decompose to give U₃O₈ as the end product through their respective uranyl dicarboxylate intermediates. Malate and oxydiacetate compounds decompose exothermically in a single step. The coordinated water is confirmed from thermal data. The complexes of succinate to sebacate seem to possess hexagonal bipyramidal geometry around uranium, whereas pentagonal bipyramidal geometry has been proposed for both malate and oxydiacetate complexes. This revised version was published online in August 2006 with corrections to the Cover Date.