Tricaesium tris­(pyridine-2,6-dicarboxyl­ato-κ3 O 2,N,O 6)lutetium(III) octa­hydrate

Colourless block crystals of the title compound, Cs(3)[Lu(dipic)(3)]·8H(2)O [dipic is dipicolinate or pyridine-2,6-dicarboxyl-ate, C(7)H(3)NO(4)] 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 mol-ecules 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(+), H(2)O] cationic planes. In the crystal structure, although the H atoms attached to water mol-ecules could not be located, short O-O contacts clearly indicate the occurrence of an intricate hydrogen-bonded network through contacts with other water mol-ecules, Cs cations or with the O atoms of the dipicolinate ligands.