Pressure- and temperature-induced valence tautomeric interconversion in a o-dioxolene adduct of a cobalt-tetraazamacrocycle complex

An electronic switch at the molecular level has been realized by using a cl ass of ionic compounds of the formula [Co(L)(diox)]Y (L=tetraazamacrocyclic ligand, Y=mononegative anion). Such compounds undergo temperature- and pre ssure-induced intramolecular one-electron transfer equilibria. The transiti on temperature of interconversion varies with the nature of the counterions Y (Y=PF6, BPh4, I). Surprisingly the effect of the anion on the transition temperature is not only governed by its volume but also by its coulombic i nteraction.