Equilibria and structure of the lanthanide(III)-2-hydroxy-1,3-diaminopropane-N,N,N',N'-tetraacetate complexes: Formation of alkoxo-bridged dimers in solid state and solution

The complex formed between 1,3-diamino-2-hydroxypropane-N,N,N',N'-tetraacetic acid and [Nd.sup.3+] at pH 7.5 is found to be a dinuclear dimer in the solid state, in which the alcoholic OH groups are deprotonated, and the alkoxo oxygens are coordinated to both [Nd.sup.3+] in a bridging position. Results of NMR studies of the [La.sup.3+] complex, the number and multiplicity of signals, and values of coupling constants are in agreement with the dinuclear dimer structure of the complex in solution.