Structural determination of new eight-coordinate NH4[EuIII(Cydta)(H2O)2]·4.5H2O and K2[Eu 2 III (pdta)2(H2O)2]·6H2O complexes

Abstract

The NH4[EuIII(Cydta)(H2O)2]·4.5H2O (I) (H4Cydta = trans-1,2-cyclohexanediamine-N,N,N′,N′-tetraacetic acid) and K2[Eu 2 III (pdta)2(H2O)2]·6H2O (II) (H4pdta = propylenediamine-N,N,N′,N′-tetraacetic acid) complexes are prepared by heat-refluxing and acidity-adjusting methods respectively, and their composition and structures are determined by elemental analyses and single crystal X-ray diffraction techniques. The complex I has a mononuclear structure, crystallizes in the triclinic crystal system with the \(P\bar 1\) space group; the central EuIII ion is eight-coordinated by a hexadentate Cydta ligand and two water molecules. The crystal data are as follows: a = 8.653(4) A, b = 10.041(4) A, c = 14.405(6) A, α = 88.469(6)°, β = 74.892(6)°, γ = 88.256(7)°, V = 1207.5(9) A3, Z = 1, D c = 1.731 g/cm3, μ = 2.669 mm−1, F(000) = 638, R = 0.0257, and wR = 0.0667 for 3807 observed reflections with I ≥ 2σ(I). The EuN2O6 part in the [EuIII(Cydta)(H2O)2]− complex anion forms a pseudo-square antiprismatic polyhedron. The complex II is eight-coordinate as well; it is a binuclear structure that crystallizes in the monoclinic crystal system with the C 2/c space group; half of the central EuIII ion is coordinated by two nitrogen atoms from one hexadentate pdta ligand and six oxygen atoms from the same pdta ligand, one water molecule and carboxylic group from the neighboring pdta ligand respectively. The crystal data are as follows: a = 19.866(3) A, b = 9.1017(12) A, c = 21.010(3) A, β = 104.972(2)°, V = 3670.1(9) A3, Z = 8, D c = 2.046 g/cm3, μ = 3.710 mm−1, F(000) = 2240, R = 0.0213 and wR = 0.0460 for 4183 observed reflections with I ≥ 2σ(I). Otherwise, the two EuN2O6 parts in the [Eu 2 III (pdta)2(H2O)2]2− complex anion form a pseudo-square antiprismatic polyhedron.