A trinuclear {(Fe2FeII)-Fe-III} complex involving both spin and non-spin transitions exhibits three-step and wide thermal hysteresis

The engineering of switchable molecules with magnetic multistability is lying on the cutting-edge research topics for integrating multi-switches and ternary memory devices. Here we presented a cyanide-bridged {(Fe2FeII)-Fe-III} desolvated complex {[(pzTp)Fe-III-(CN)(3)](2)[Fe-II(L)]} (1), obtained through single-crystal-to-single-crystal (SCSC) transformation from its solvated phase {[(pzTp)-Fe-III(CN)(3)](2)[Fe-II(L)]}center dot 2CH(3)OH center dot 5H(2)O (1 center dot sol). Remarkably, 1 exhibited unprecedented three-step transition in magnetization with wide thermal hysteresis (44, 40, and 36 K) in the temperature range of 80-320 K. The detailed studies demonstrated that the tristable character originates from both an order-disorder structural phase transition (SPT) and a strongly cooperative two-step spin crossover (SCO) process. This work thus provides a new promising strategy for realizing multiple bistablity in magnetization by introducing two different transitions.