Synthesis and structural determination of the first eight-coordinate rare earth metal complex with a six-member ring, (NH4)[EuIII(pdta)(H2O)] · H2O

Abstract

(NH4)[EuIII(pdta)(H2O)] · H2O has been synthesized and characterized by infrared spectrum, fluorescence spectrum, elemental analyses and single-crystal X-ray diffraction techniques. It crystallizes in the monoclinic system with space group P21/n, a = 12.7700(15) Å, b = 9.3885(11) Å, c = 14.4070(18) Å, α = 90°, β = 95.950(2)°, γ = 90°, V = 1718.0(4) Å3, Z = 4, M = 508.28, D c = 1.965 g cm−3, μ = 3.708 mm−1, F(000) = 1108. The structure was refined to R 1 = 0.0238 for 3469 observed reflections (I > 2σ(I)). The EuIIIN2O6 part in the [EuIII(pdta)(H2O)]− complex anion has an eight-coordinate structure with a distorted square anti-prismatic conformation, in which six coordination positions, two nitrogen atoms and four oxygen atoms are from one pdta (=propylenediaminetetraacetic acid) ligand, the seventh position is an oxygen (O(8A)) from another pdta and the eighth coordination site is occupied by a water molecule. (NH4)[EuIII(pdta)(H2O)] · H2O is the first eight-coordinate complex with a six-member ring in the rare earth metal complexes with aminopolycarboxylic acid ligands.