STRUCTURAL SYSTEMATICS OF RARE-EARTH COMPLEXES .7. CRYSTAL-STRUCTURE OF BIS(2,2' 6',2''-TERPYRIDINIUM) OCTAAQUATERBIUM(III) HEPTACHLORIDE HYDRATE/

The room-temperature single-crystal X-ray structural characterization of the title compound (tpyH2)2[Tb(OH2)8]Cl7.approximately 2 1/3H2O is recorded. Crystals are triclinic, P1BAR, a 17.063(5), b 16.243(3), c 7 .878(3) angstrom, alpha 84.78(2), beta 84.39(3), gamma 87.81(2)-degree s, Z = 2 formula units; 3167 'observed' diffractometer reflections wer e refined by full-matrix least-squares procedures to a residual of 0.0 57. Notable features of interest of the compound are the 'chelation' o f chloride ions by the terpyridinium cations, and the existence of a f ree [Tb(OH2)8]2+ cation in the presence of an abundance of chloride io ns.