Crystal structure of dicaesium strontium hexa­cyanidoferrate(II), Cs(2)Sr[Fe(CN)(6)], from laboratory X-ray powder data

Ferrocyanides with general formula A (I) (x)B (II) (y)[Fe(CN)(6)], where A and B are cations, are thought to accept many substitutions on the A and B positions. In this communication, the synthesis and crystal structure of Cs(2)Sr[Fe(CN)(6)] are reported. The latter was obtained from K(2)Ba[Fe(CN)(6)] particles, put in contact with caesium and strontium ions. Hence, a simultaneous ion-exchange mechanism (Cs for K, Sr for Ba) occurs to yield Cs(2)Sr[Fe(CN)(6)]. The synthesis protocol shows that K(2)BaFe(CN)(6) particles can be used for the simultaneous trapping of radioactive caesium and strontium nuclides in water streams. Cs(2)Sr[Fe(CN)(6)] adopts the cryolite structure type and is isotypic with the known compound Cs(2)Na[Mn(CN)(6)] [dicaesium sodium hexa­cyanidomanganate(III)]. The octa­hedrally coordinated Sr and Fe sites both are located on inversion centres, and the eightfold-coordinated Cs site on a general position.