STRUCTURAL-ANALYSES OF 2 HEXACYANORUTHENATE(II) COMPLEXES

Refinements of the crystallographic structures of GdKRu(CN)(6) . 4H(2) O and TbKRu(CN)(6) . 4H(2)O have been carried out by means of three-di mensional single-crystal X-ray diffractometry. These ruthenate(II) com plexes crystallize in the orthorhombic space group Cmcm (Z=4) with res pective lattice constants of a=7.460(2) and 7.440(2), b=12.845(2) and 12.807(2), and c=14.334(5) and 14.293(3) Angstrom. The structural data were anisotropically refined using a full-matrix least-squares progra m. The final reliability (R) factors of 0.024 and 0.030 were based on 1070 and 1070 unique reflections for the Gd and To complexes, respecti vely. The eight-coordinated lanthanide (Ln) atoms are bonded to six cy anonitrogen atoms and two water molecules in a square-antiprism geomet ry (D-4d), the LnN(6)(H2O)(2) group. The ruthenium ions are octahedral ly coordinated to six cyanocarbon atoms, the RuC6 group. Cyanide bridg ing links these groups to build an infinite polymeric array. Cavities within the structures are occupied by K ions and uncoordinated water m olecules. The latter are within hydrogen bonding distance to the coord inated water molecules. Notable bond lengths and angles have been tabu lated and infrared and thermal gravimetric studies are presented.