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  • STRUCTURAL CHARACTERIZATION OF A TERBIUM (III) COMPLEX WITH 1,4,8,11-TETRAAZACYCLOTETRADECANE-1,4,8,11-TETRAACETIC ACID, LANTHANIDE IONS AND THE CONFORMATION OF THE 14-MEMBERED MACROCYCLES

Abstract

The molecular and crystal structure of Na-(Tb-TETA)-(H-2O)-6(NaCl)-0,5 (TETA = 1,4,8,11-tetraazacyclotetradecane-1,4,8,11-tetraacetic acid) has been determined from three-dimensional X-ray intensity data. The space group is P2/c, and the lattice parameters are a = 17.980 Angstroem, b = 9.081 Angstroem, c = 17.713 (3) Angstroem, ss = 106.00 degrees, and d = 1.775 g/cm**3 for Z = 4. The structure was solved by direct methods. Full-matrix least-squares refinement with all non-hydrogen atoms treated anisotropically gave an agreement factor R of 0.0036 for 4111 unique reflections. The Tb**3+ ion is eight-coordinated, being linked to the four nitrogen atoms and the four carboxylic oxygen atoms of the ligand. The coordination polyhedron of the terbium ion is a strongly distorted dodecahedron, but although no symmetry is imposed by the space group, the TETA ligand approximates the C-2 symmetry fairly well. The conformation of the 14-membered macrocyclic ring is compared with the various conformations adopted by other macrocycles with the same cavity size. The TETA ligand exhibits a biangular {77} structure, which is the most suited for the complexation of a 4f metal ion located out of the mean plane of the macrocyclic ring. In the crystal, the (TbTETA)-anion complex units are associated through sodium ions and water molecules into layers that alternate with aqueous layers containing the chloride ions.

Additional information

Authors: SPIRLET M R, UNIVERSITY OF LIEGE (BELGIUM);JRC KARLSRUHE ESTAB. (GERMANY);REBIZANT J, UNIVERSITY OF LIEGE (BELGIUM);JRC KARLSRUHE ESTAB. (GERMANY);LONCIN M F, UNIVERSITY OF LIEGE (BELGIUM);JRC KARLSRUHE ESTAB. (GERMANY);DESREUX J F UNIVERSITY OF LIEGE (BELGIUM), UNIVERSITY OF LIEGE (BELGIUM);JRC KARLSRUHE ESTAB. (GERMANY);JRC KARLSRUHE ESTAB. (GERMANY), UNIVERSITY OF LIEGE (BELGIUM);JRC KARLSRUHE ESTAB. (GERMANY)
Bibliographic Reference: INORGANIC CHEMISTRY, VOL. 23 (1984), PP. 4278-4283
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