Synthesis of Lanthanoid Complexes from Ln2O3 and Diatrizoic Acid

We present a pathway to synthesize diatrizoate lanthanoid complexes directly from Ln2O3 and diatrizoic acid (DTAH = 3,5-diacetamido-2,4,6-triiodobenzoic acid) at room temperature yielding [Ln(H2O)8][DTA]3 in moderate (for the heavier lanthanoids) to good (for the lighter lanthanoids) yields. Compounds were recrystallized from DMSO or water and their X-ray crystal structures were obtained. The complexes have metal centres solely coordinated by solvent molecules with no direct interaction between the metal centre and the DTA anion. The compounds crystallized from DMSO have the formulation [Ln(DMSO)4(H2O)4][DTA]3.DMSO (Ln = La, Nd, Sm, Eu, Dy; only unit cell data were confirmed for Ln = Nd, Sm) whereas the compound crystallized from water has the formulation [Dy(H2O)8][DTA]3.7H2O.