Magnetic Multistability in an Anion-Radical Pimer.

Radical pimers are the simplest and most important models for studying charge-transfer processes and provide deep insight into π-stacked organic materials. Notably, radical pimer systems with magnetic bi- or multistability may have important applications in switchable materials, thermal sensors, and information-storage media. However, no such systems have been reported. Herein, we describe a new pimer consisting of neutral N-(n-propyl) benzene triimide ([BTI-3C]) and its anionic radical ([BTI-3C]-. ) that exhibits rare magnetic multistability. The crystalline pimer was readily synthesized by reduction of BTI-3C with cobaltocene (CoCp2 ). The transition occurred with a thermal hysteresis loop that was 27 K wide in the range of 170-220 K, accompanied by a smaller loop with a width of 25 K at 220-242 K. The magnetic multistability was attributed to slippage of the π-stacked BTI structures and entropy-driven conformational isomerization of the side propyl chains in the crystalline state during temperature variation.