A counter ion triggers stabilization of two geometrical isomers of a Ni(ii) dication diradical porphyrin dimer: The role of anion-π interactions

Two geometrical isomers of a nickel(ii) dication diradical porphyrin dimer have been isolated selectively in pure forms by step-wise addition of the oxidant in the same reaction pot. Both isomers, stabilized exclusively by anion-π interactions, have unique and very distinct electronic and spectroscopic features and display an anion-induced charge/electron transfer phenomenon. Our work highlights the crucial role played by counter ions in controlling and stabilizing a variety of electronic structures and potentiates the effect of anion-π interactions in the chemical, biological and materials world.