Energetic and Constitutional Hysteresis in Bistable Molecules

A macrocycle containing [Ru(NH3)5]S and [Ru(NH3)5]SO functions (shown on the right) was recently employed by Taube and Sano as a bistable system, which, like the key components of digital electronic devices, switches from one state to another when triggered by a signal. On going from RuII to RuIII, RuSO can isomerize to RuOS. Using cyclic voltammetry, Taube and sano were thus able to prepare both the SO and the OS isomer by selective redox triggering, depending on whether they started from the completely oxidized or reduced complex.