Syntheses and structures of seven-coordinate K 3 [Cd(Dtpa)], K 2 [Cd(H 2 O) 4 ][Cd(Edta)(H 2 O)] 2 · 2H 2 O, and Na 2 [Cd(H 2 O) 4 ][Cd(Edta)(H 2 O)] 2 · 2H 2 O complexes

The title complexes, K 3 [Cd(Dtpa)] (H 5 Dtpa = diethylenetriamine-N,N,N,N′,N′-pentaacetic acid, (I)), K 2 [Cd(H 2 O) 4 ][Cd(Edta)(H 2 O)] 2 · 2H 2 O (H 4 Edta = ethylenediamine-N,N,N′,N′-tetraacetic acid, (II)), and Na 2 [Cd(H 2 O) 4 ][Cd(Edta)(H 2 O)] 2 · 2H 2 O (III), were prepared, and their compositions and structures were determined by elemental analyses, IR spectra, and single-crystal X-ray diffraction techniques, respectively. In complex I, the Cd is seven-coordinated by one Dtpa ligand yielding a pseudo-monocapped trigonal prism conformation, and the complex crystallizes in the triclinic crystal system with the Pi space group. The crystal data are as follows: a = 8.7300(17), b = 9.1200(18), c = 15.110(3) Å, α = 95.52(3)°, β = 96.59(3)°, γ = 99.63(3)°, V = 1170.0(4) Å 3 , Z = 2, ρ = 1.754 g/cm 3 , μ = 1.519 mm −1 , F (000) = 616, R = 0.0644 and wR = 0.1712 for 3842 observed reflections with I ≥ 2σ( I ). For complex II, in the [Cd(Edta)(H 2 O)] 2− complex anion the Cd 2+ ion is seven-coordinated by one Edta ligand and one water molecule, yielding a pseudo-pentagonal bipyramid conformation. In the [Cd(H 2 O) 4 ] 2+ cation, the bridged Cd is six-coordinated, yielding an almost standard octahedral conformation. The complex crystallizes in the monoclinic system with P 2 1 / n space group. The crystal data are as follows: a = 9.098(3), b = 16.442(6), c = 12.023(4) Å, β = 91.053(6)°, V = 1798.3(12) Å 3 , Z = 2, ρ = 2.098 g/cm 3 , μ = 2.086 mm −1 , F (000) =1124, R = 0.0406 and wR = 0.1152 for 3680 observed reflections with I ≥ 2σ( I ). In complex III, the conformations of Cd 2+ ions are similar to those of the potassium salt complex, and the complex also crystallizes in the monoclinic crystal system with the P 2 1 / n space group. The crystal data are as follows: a = 9.134(7), b = 16.500(13), c = 12.075(10) Å, β = 91.054(12)°, V = 1820(2) Å 3 , Z = 2, ρ = 2.015 g/cm 3 , μ = 1.856 mm −1 , F (000) = 1092, R = 0.0363 and wR = 0.0879 for 3707 observed reflections with I ≥ 2σ( I ).