Tricaesium tris(pyridine-2,6-dicarboxylato-κ3O2, N,O6)lutetium(III) octahydrate

Colourless block crystals of the title compound, Cs-3[Lu(di-pic) (3)] center dot 8H(2)O [dipic is dipicolinate or pyridine-2,6-dicarboxylate, C7H3NO4] were synthesized by slow evaporation of the solvent. The crystal structure of this Lu-III-complex, isostructural with the Dy-III and Eu-III complexes, was determined from a crystal twinned by inversion and consists of discrete [Lu(dipic)(3)](3)-anions, Cs+ cations and water molecules involving hydrogen bonding. The Lu atom lies on a twofold rotation axis and is coordinated by six O atoms and three N atoms of three dipicolinate ligands. One Cs atom is also on a twofold axis. The unit cell can be regarded as successive layers along the crystallographic c-axis formed by [Lu(dipic)(3)](3-) anionic planes and [Cs+, H2O] cationic planes. In the crystal structure, although the H atoms attached to water molecules could not be located, short O-O contacts clearly indicate the occurrence of an intricate hydrogen-bonded network through contacts with other water molecules, Cs cations or with the O atoms of the dipicolinate ligands.