Syntheses and crystal structures of nine-coordinate K2[EuIII(dtpa)(H2O)]·5H2O and Na2[TbIII(Httha)]·6H2O complexes

Abstract

The title complexes, K2[EuIII(dtpa)(H2O)]·5H2O (H5dtpa = diethylenetriamine-N,N,N′,N″,N″-pentaacetic acid), Na2[TbIII(Httha)]·6H2O (H6ttha = triethylenetetramine-N,N,N′,N′,N″,N″-hexaacetic acid), were prepared, and their compositions and structures were determined by elemental analyses and single-crystal X-ray diffraction techniques. The crystal of K2[EuIII(dtpa)(H2O)]·5H2O belongs to triclinic crystal system and \( P\bar 1 \) space group. The crystal data are as follows: a = 8.3540(17), b = 10.147(2), c = 15.059(3) α = 84.63(3)A, β = 82.02(3)°, γ = 83.96(3)°, V = 1253.1(4)A3, Z = 2, R = 0.0325 and wR = 0.1013 for 4407 observed reflections with I ≥ 2σ(I). The [EuIII(dtpa)(H2O)]2− has a nine-coordinate pseudo-monocapped square antiprismatic structure, in which the nine coordinate atoms, three N and six O are from one dtpa ligand and one water molecule. The crystal of the Na2[TbIII(Httha)]·6H2O belongs to monoclinic system and P21/c space group. The crystal data are as follows: a = 10.3976(10), b = 12.7908(13), c = 23.199(2) A = 90.914(2)°, V = 3084.9(5)A3, Z = 4, R = 0.0309 and wR = 0.0704 for 5429 observed reflections with I ≥ 2σ(I). In the [TbIII(Httha)]2−, the Tb3+ ion is nine-coordinated yielding a pseudo-monocapped square antiprismatic conformation, in which the ttha ligand coordinates to the central Tb3+ ion with four N atoms and five O atoms. There is a free non-coordinate carboxyl group (−CH2COOH) that can be modified by some biological molecules having target function.