Structural analyses of two hexacyanoruthenate(II) complexes

Abstract

Refinements of the crystallographic structures of GdKRu(CN) 6·4H 2O and TbKRu(CN) 6·4H 2O have been carried out by means of three-dimensional single-crystal X-ray diffractometry. These ruthenate(II) complexes crystallize in the orthorhombic space group Cmcm ( Z=4) with respective 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) A ̊ . The structural data were anisotropically refined using a full-matrix least-squares program. The final reliability ( R) factors of 0.024 and 0.030 were based on 1070 and 1070 unique reflections for the Gd and Tb complexes, respectively. The eight-coordinated lanthanide (La) atoms are bonded to six cyanonitrogen atoms and two water molecules in a square-antiprism geometry ( D 4 d ), the LnN 6(H 2O) 2 group. The ruthenium ions are trahedrally coordinated to six cyanocarbon atoms, the RuC 6 group. Cyanide bridging links these groups to build an infinite polymeric array. Cavities within the structures are occupied by K ions and uncoordinated water molecules. The latter are within hydrogen bonding distance to the coordinated water molecules. Notable bond lengths and angles have been tabulated and infrared and thermal gravimetric studies are presented.