Crystal structure of dicaesium strontium hexa-cyanidoferrate(II), CsSr[Fe(CN)], from laboratory X-ray powder data.

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