The series of solid solutions Y[Fe1−xCox(CN)6]·4H2O (0 ⩽ x ⩽ 1) were prepared and characterized by means of powder X-ray diffraction (PXRD), Infrared and Mössbauer spectroscopy and magnetic measurements. The thermal decomposition process has been followed by thermogravimetric and differential thermal analysis (TGA–DTA). The crystal structure of the complexes was refined by means of Rietveld analysis. The Y[Fe1−xCox(CN)6]·4H2O complexes crystallize in the orthorhombic crystal system, space group Cmcm. The Y3+ ion is eight-coordinated forming a bicapped distorted trigonal prism YN6O2. The Fe3+ and Co3+ ions are six-coordinated in the form of an irregular octahedra (Fe,Co)C6 group and cyanide linkages between YN6O2 and (Fe,Co)C6 groups build an infinite polymeric array. The Mössbauer spectra of all solid solutions Y[Fe1−xCox(CN)6]·4H2O present quadrupolar splittings with negative isomer shifts values due to the existence of a strong π back-bonding effect from the Fe3+ ion towards the CN ligands. All compounds follow the Curie–Weiss law showing anti-ferromagnetic interactions at very low temperatures.
