AQUO-(1,4,7,10-TETRAAZA0CYCLODODECANE-1,4,7,10-TETRAACETATO) - EUROPIUM-(III) TETRAHYDRATE, NA + (EUDOTA.H-2O)RU-.4H-2O
N+ (EuDOTA.H-2O)RU-.4H-2O crystallizes in space group Ppdelta 1 with cell dimensions a = 8.710 ANGSTROEM, b = 9.120 ANGSTROEM, c = 15.742 ANGSTROEM, alpha = 92.87 degrees, beta = 85.43 degrees . d(calcd) = 1.797 g cm**-3 for Z = 2. The crystal structure was solved by direct methods. Full matrix least squares refinement with all non-hydrogen atoms treated anisotropically gave an agreement factor R of 0.032 for 3142 unique reflections. The europium ion is nine coordinate, being linked to the four nitrogen atoms of DOTA and to four carboxyl oxygen atoms of this ligand as well as to one hydration water molecule. The coordination polyhedron can be described as a distorted capped square antiprism. The crystal packing consists of parallel EuDOTA chains that are linked, alternatively, through six-membered water rings, hydrogen bonded to carboxyl oxygens, and through Na+ ions and water molecules that form a pattern of Na-O and O-O short contacts with carboxyl oxygens. The overall conformation of the macrocyclic ring, in spite of its partially asymmetric nature, is very close to a  square in keeping with the stereochemical arrangement deduced from previous NMR studies. The relative NMR dipolar shifts computed from the solid-state structure of EuDOTA**- and induced in solution by Yb**3+ are in very good agreement, thus suggesting that the lanthanide DOTA complexes are unusually rigid.
Bibliographic Reference: INORGANIC CHEMISTRY, VOL. 23 (1984), PP. 359-363
Record Number: 1989122077900 / Last updated on: 1987-01-01
Available languages: en