Crystal Structures of Members in Isostructural Series: Prediction of the Crystal Structure of Cs2MnO4 - a p-K2SO4 Type Isomorph

Recent studies have shown that the crystal structure of members within a group of isostructural compounds may be successfully predicted. The P-K2SO4 group isomorphs of the general formula M2XO4 were chosen as a family of closely related compounds for which accurately refined crystal structures exist. It is shown that the unit cell parameters and the fractional atomic coordinates exhibit systematic variations with both cation and anion size, as well as with the Mulliken charge of the oxygen atom in the tetrahedral anion. It is thus possible to predict the crystal structure of a given member in the series only on the basis of its chemical composition. The structure of Cs2MnO4 predicted in this way is compared with the one refined earlier by X-ray diffraction. The agreement be- tween the structural parameters in both structures is very good