Syntheses of the Eight-Coordinate NH4[ErIII(Cydta)(H2O)2] • 4.5H2O and (NH4)2[Er2III(Pdta)2(H2O)2] • 2H2O Complexes and Their Structural Investigation

In this work, the title complexes, NH4[Er-III(Cydta)(H2O)(2)] center dot 4.5H(2)O (I) (H(4)Cydta = trans-1,2-cyclo-hexanediamine-N,N,N',N'-tetraacetic acid) and (NH4)(2)[Er-2(III)(Pdta)(2)(H2O)(2)] center dot 2H(2)O (II) (H(4)Pdta=propylene-diamine-N,N,N',N'-tetraacetic acid), were prepared, respectively, and their composition and structures were determined by elemental analyses and single-crystal X-ray diffraction techniques. Complex I selects a mononu-clear structure with pseudosquare antiprismatic geometry crystallized in the triclinic crystal system with space group P (1) over bar and the central Er3+ ion is eight-coordinated by the hexadentate Cydta ligand and two water molecules. The crystal data are as follows: a = 8.568(3), b = 10.024(3), c = 14.377(4) angstrom, alpha = 88.404(4)degrees, beta = 75.411(4)degrees, gamma = 88.332(4)degrees, V = 1194.2(6) angstrom(3), Z = 1, rho(c) = 1.793 g/cm(3), mu = 3.586 mm(-1), F(000) = 648, R = 0.0257, and wR = 0.0667 for 4169 observed reflections with I >= 2 sigma(I). Complex II is eight-coordinated as well, which selects a binuclear structure with two pseudosquare antiprismatic geometry and crystallizes in the monoclinic crystal system with space group P2(1)/n. The central Er3+ ion is coordinated by two nitrogens and four oxygens from one hexadentate Pdta ligand. Besides, two oxygens come from one carboxylic group of the neighboring Pdta ligand and one water molecule, respectively. The crystal data are as follows: a = 12.7576(8), b = 9.3151(6), c = 14.3278(9) angstrom, beta = 96.1380(10)degrees, V = 1692.93(19) angstrom(3), Z = 4, rho(c) = 2.054 g/cm(3), mu = 5.015 mm(-1), F(000) = 1028, R = 0.0228, and wR = 0.0534 for 2984 observed reflections with I >= 2 sigma(I).