Exceptional Dielectric Phase Transitions in a Perovskite‐Type Cage Compound

Rotation does work! The organic–inorganic hybrid cage compound (HIm)2[KFe(CN)6] (1, HIm=imidazolium) with a perovskite-type structure exhibits two phase transitions at 158 K and 187 K (see picture showing anisotropic dielectric permittivities of the single crystal). These transitions are due to order–disorder behavior of rotatable guest molecules. Compound 1 is a new class of switchable molecular dielectric with striking anomalies and anisotropy.