Syntheses and structures of seven-coordinate K3[Cd(Dtpa)], K2[Cd(H2O)4][Cd(Edta)(H2O)]2 • 2H2O, and Na2[Cd(H2O)4][Cd(Edta)(H2O)]2 • 2H2O 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) center dot 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) center dot 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) angstrom, alpha = 95.52(3)degrees, beta = 96.59(3)degrees, gamma = 99.63(3)degrees, V = 1170.0(4) angstrom(3), Z = 2, rho = 1.754 g/cm(3), mu = 1.519 mm(-1), F(000) = 616, R = 0.0644 and wR = 0.1712 for 3842 observed reflections with I >= 2 sigma(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 P2(1)/n space group. The crystal data are as follows: a = 9.098(3), b = 16.442(6), c = 12.023(4) angstrom, beta = 91.053(6)degrees, V = 1798.3(12) angstrom(3), Z = 2, rho = 2.098 g/cm(3), mu = 2.086 mm(-1), F(000) =1124, R = 0.0406 and wR = 0.1152 for 3680 observed reflections with I >= 2 sigma(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 P2(1)/n space group. The crystal data are as follows: a = 9.134(7), b = 16.500(13), c = 12.075(10) angstrom, beta = 91.054(12)degrees, V = 1820(2) angstrom(3), Z = 2, rho = 2.015 g/cm(3), mu = 1.856 mm(-1), F(000) = 1092, R = 0.0363 and wR = 0.0879 for 3707 observed reflections with I >= 2 sigma(I).