The crystal structure of four cyanometallates has been determined from X-ray powder diffraction data using the Rietveld method. The variously hydrated compounds Cu3[Co(CN)6]2, Mn3[Co(CN)6]2 and KNi[Fe(CN)6] crystallize at cubic symmetry (Fm3m) with lattice parameters 10.032(2), 10.413(3) and 10.234(5) Å, respectively. The crystal of KMn[Fe(CN)6]·2H2O shows a monoclinic structure (P21/c) with the lattice parameters a=10.108(2) Å, b=10.104(3) Å, c=10.114(3) Å, β=92°, 93°. The starting model was based on an isomorphic Mn3[Co(CN)6]2 single crystal structure, where Co and Mn ions are octahedrally coordinated by C and N atoms, respectively, forming three-dimensional bimetallic networks with the C≡N groups as bridging ligands.
