Design of ferromagnetic alternating stacks of neutral and ion-radical hydrocarbons

Alternating stacks of π-radicals and diamagnetic subunits are considered in detail as an extension of earlier work. Such alternating stacks are predicted to avoid the typical antiferromagnetic spin-exchange of identical face-to-face radicals via spin polarization of the diamagnetic spacer in between. It is shown here that neutral spin carriers like perinaphthenyl 2 and periperylenyl 3 are very promising candidates if alternatingly stacked with aromatics like pyrene, perylene or coronene to achieve effective ferromagnetic coupling along the crystal stack, while ion-radicals of aromatic hydrocarbons are not an equally good choice since partial charge transfer suppresses intermolecular spin polarization. The influence of structural factors on the effective exchange is discussed, too.