Nine-coordinate dinuclear Na6[Gd2III(Ttha)2] · 8H2O and mononuclear (H2En)3[GdIII(Ttha)]2 · 11H2O complexes: Synthesis and structural determination

The Na6[Gd2III(Ttha)2] · 8H2O (I) (H6Ttha = triethylenetetramine-N,N,N′,N″,N‴,N‴-hexaacetic acid) and (H2En)3[GdIII(Ttha)]2 · 11H2O (II) (En = ethylenediamine) complexes were prepared with heat-refluxing and acidity-adjusting methods, respectively. Their composition and structures were determined by elemental analysis and single-crystal X-ray diffraction techniques. Complex I shapes a binuclear and nine-coordinated structure and crystallizes in the orthorhombic crystal system with space group Pccn. The central Gd3+ ion is coordinated with one Ttha ligand by three N atoms and four O atoms and with one adjacent Ttha ligand by two O atoms. The crystal data are as follows: a = 26.036(13) Å, b = 21.007(10) Å, c = 22.694(12) Å, V = 12412(11) Å3, Z = 8, c = 1.699 g/cm3, μ = 2.254 mm−1, F(000) = 6368, R = 0.0602, and wR = 0.1146 for 3434 observed reflections with I ≥ 2σ(I). The GdN3O6 part in the [Gd2III(Ttha)2]6− complex anion forms a pseudo-tricapped trigonal prismatic geometry. Complex II is also nine-coordinate, but mononuclear and crystallizes in the monoclinic crystal system with space group P21/n. While the central Gd3+ ion is coordinated by four nitrogen atoms and five oxygen atoms from the same Ttha ligand. The crystal data are as follows: a = 17.7726(17) Å, b = 19.2942(17) Å, c = 20.6045(19) Å, β = 111.4600(10)°, V = 6575.6(10) Å3, Z = 8, c = 1.693 g/cm3, μ = 2.102 mm−1, F(000) = 3428, R = 0.0333 and wR = 0.0827 for 14792 observed reflections with I ≥ 2σ(I). Otherwise, the GdN4O5 part in each [GdIII(Ttha)]3− complex anion adopts a pseudo-monocapped square antiprismatic polyhedron.