Rare earth metal complexes with triethylenetetraminehexaacetic acid

Abstract

The crystal and molecular structures of K4[(Httha)2]·13.5H2O (ttha = triethylenetetraminehexaacetic acid), K4[(Httha)2]·14H2O, K3[DyIII (ttha)]·5H2O, K3[HoIII(ttha)]·5H2O and K3[ErIII(ttha)]·5H2O have been determined by single-crystal X-ray structure analyses. The crystal data of these five complexes are as follows: (1) K4[(Httha)2]·13.5H2O, monoclinic crystal system, P2(1)/n space group, Z = 4, μ = 2.339 mm−1 and F(000) = 3404. The final R and wR are 0.0514 and 0.0906 for 11,144 [I > 2.0 σ(I)] unique reflections, and 0.0976 and 0.1068 for all 26,048 reflections, respectively. (2) K4[(Httha)2]·14H2O, monoclinic crystal system, P2(1)/n space group, Z = 4, μ = 2.611 mm−1 and F(000) = 3424. The final R and wR are 0.0339 and 0.0667 for 10,699 [I > 2.0 σ(I)] unique reflections, and 0.0543 and 0.0741 for all 22,190 reflections, respectively. (3) K3[DyIII(ttha)]·5H2O, monoclinic crystal system, P2(1)/c space group, Z = 4, μ = 3.096 mm−1 and F(000) = 1716. The final R and wR are 0.0252 and 0.0600 for 5905 [I > 2.0 σ(I)] unique reflections, and 0.0336 and 0.0629 for all 16,415 reflections, respectively. (4) K3[HoIII(ttha)]·5H2O, monoclinic crystal system, P2(1)/c space group, Z = 4, μ = 3.217 mm−1 and F(000) = 1720. The final R and wR are 0.0395 and 0.0796 for 5145 [I > 2.0 σ(I)] unique reflections, and 0.0546 and 0.0833 for all 11,567 reflections, respectively. 5. K3[ErIII(ttha)]·5H2O, monoclinic crystal system, P2(1)/c space group, Z = 4, μ = 3.398 mm−1 and F(000) = 1724. The final R and wR are 0.0212 and 0.0463 for 5130 [I > 2.0 σ(I)] unique reflections, and 0.0258 and 0.0477 for all 11,796 reflections, respectively. The structure of K4[(Httha)2]·13.5H2O is composed of two parts, each has a binuclear nine-coordinate structure with distorted monocapped square antiprismatic prisms, in which the ttha ligand coordinates to one central EuIII ion with three N atoms and four O atoms and to the other EuIII ion with two O atoms. The K4[(Httha)2]·14H2O complex molecule is also composed of two parts in structure, each part has a binuclear nine-coordinate structure with distorted tri-capped trigonal prism. The [DyIII(ttha)]3− complex anion has a mononuclear nine-coordinate structure with distorted monocapped square antiprismatic geometry, in which the ttha ligand coordinates to the central DyIII ion with four N atoms and five O atoms. The [HoIII(ttha)]3− and [ErIII(ttha)]3− complex anions also have nine-coordinate structures, but the geometric conformation is close to a distorted tricapped trigonal prism. In addition, there is a free non-coordinated carboxyl group (–CH2COO−) in the [HoIII(ttha)]3− and [ErIII(ttha)]3− complex anions. The free carboxyl group could be embellished by biological molecules which have selectivity and affinity to focus positions.