Observation of novel dielectric bistability in a nickel-dithiolene ion-pair compound

An ion-pair compound, 1,10-bis(1-methylimidazolium)decane bis(maleonitriodithiolato)nickelate (1), was synthesized and single crystal structurally characterized. The bis(maleonitriodithiolato)nickelate anions and dication formed the layered stacks in the crystal. A dielectric relaxation was observed in low-frequency region and could be attributed to local dipole or molecular motion in 1. The relaxation process for 1 was fitted using Cole–Cole model function. Furthermore, this ion-pair compound shows novel dielectric bistability and dielectric phase transition around 90 °C, which is probably arise from the disorder-to-order transformation of alkyl chains and the conformation rotation of imidazolyl rings. This study provided a new strategy for the design of dielectric bistable system.