Inorganic Co-Crystal Formation and Thermal Disproportionation in a Dicyanometallate 'Superperovskite'

We report the synthesis, crystal structure, and thermally- driven phase transformation of the dicyanometallate super- perovskite co-crystal [NBu4]Mn[Au(CN)2]3·[NBu4]ClO4. This phase is understandable in terms of the conventional ABX3 perovskite structure type, but with the NBu+4 A-site cation displaced onto the perovskite cage face and 1-dimensional AX′ chains included within framework pores opened up by these displacements. On heating to 380K, the co-crystal disproportionates into its two inorganic components: a bcs-structured ABX3 phase and [NBu4 ]ClO4 . This system illustrates a new type of structural and phase complexity accessible to dicyanometallate perovskites.