Uranyl complexes with acyclic compartmental ligands

A series of mononuclear and binuclear uranyl(VI) complexes have been prepared by using Schiff bases derived from o-acetoacetylphenol, 2-acetyl-1,8-dihydroxy-3,6-dimethylnaphthalene, diacetylacetone, benzoylacetylacetone and polyamines of the type NH2(CH2)nNH2 or NH2(CH2)nX(CH2)nNH2 (X=NH, O, S). In some cases a template synthesis was used. With diacetylacetone acyclic and cyclic Schiff bases have been obtained for X=S but not for X=NH. With these precursors, or with preformed ligands, nickel(II) and copper(II) complexes have been also prepared. Homodinuclear uranyl complexes of Schiff bases may be obtained provided steric problems are overcome and a large flexible ligand is used. Uranyl(VI) will attempt to make up its coordination number by use of solvent but this can be avoided by using amines with extra donor atoms in the Schiff base and thus encouraging interaction with five donor atoms in a ligand compartment. (orig.)