Abstract: | The complex phosphate tricaesium calcium iron bis(diphosphate), Cs3CaFe(P2O7)2, has been prepared by the flux method. Isolated [FeO5] and [CaO6] polyhedra are linked by two types of P2O7 groups into a three‐dimensional framework. The latter is penetrated by hexagonal channels along the a axis where three Cs atoms are located. Calculations of caesium Voronoi–Dirichlet polyhedra give coordination schemes for the three Cs atoms as [8 + 3], [9 + 1] and [9 + 4]. The structure includes features of both two‐ and three‐dimensional frameworks of caesium double pyrophosphates. |