THE CRYSTAL AND MOLECULAR-STRUCTURE OF SODIUM HEXACYANOOSMATE(II) DECAHYDRATE AND RELATED HEXACYANOMETALATE COMPLEXES

The crystal structures of sodium hexacyanoosmate, ruthenate and ferrate decahydrates, Na4M(CN)6.10H2O (M = Os, Ru, Fe), have been determined from X-ray diffraction data and refined by full matrix least-squares to final agreement values: R = 0.038, R(w) = 0.039, R = 0.026, R(w) = 0.041; R = 0.060, R(w) = 0.043 for Os, Ru and Fe compounds, respectively. The compounds are isostructural and crystallize in the monoclinic space group P2(1)/n, Z = 2, with a = 9.154, b = 11.506, c = 9.876 angstrom, beta = 97.95-degrees; a = 9.146, b = 11.486, c = 9.867 angstrom, beta = 98.00-degrees; a = 9.038, b = 11.450, c = 9.782 angstrom, beta = 97.57-degrees, for Os, Ru and Fe compounds, respectively. The structure can be described as layers of hexacyanometallate anions, intercalated with layers of sodium polyhedra containing hydration water molecules and N atoms, perpendicular to the crystallographic ac plane. Metal-C and C-N distances for the hexacyanide anions are correlated with those from other structurally related moieties. The infrared spectra of the compounds are complementary with previous results for potassium salts.