Reversible Switching of a Cobalt Complex by Thermal, Pressure, and Electrochemical Stimuli: Abrupt, Complete, Hysteretic Spin Crossover

Triply switchable [Co^II(dpzca)₂] shows an abrupt, reversible, and hysteretic spin crossover (T_1/2↓ = 168 K, T_1/2↑ = 179 K, and ΔT_1/2 = 11 K) between the high-spin (HS) and low-spin (LS) states of cobalt(II), both of which have been structurally characterized. The spin transition is also reversibly triggered by pressure changes. Moreover, in a third reversible switching mechanism for this complex, the magnetic properties can be switched between HS cobalt(II) and LS cobalt(III) by redox.