Magnetism in organic ion radical salts and complexes based on nitronyl nitroxide

In order to study effects of magnetic and non-magnetic counter ions on the magnetism in organic radical crystals, alkali metal and transition metal salts of carboxylatofuryl nitronyl nitroxide were synthesized. Guanidinium sulfonatofuryl nitronyl nitroxide complex was also prepared and compared its magnetism with that of the sodium salt. Magnetization measurements reveal that ferromagnetic intermolecular interaction, which is coexistent with antiferromagnetic one, in 2-carboxyfuryl nitronyl nitroxide is disappeared by inserting alkali-metal ions. Insertion of manganese, cobalt and copper ions into 2-carboxyfuryl nitronyl nitroxide results in complex behavior, suggesting in part ferromagnetic interaction, in temperature dependence of magnetic susceptibility. Replacement of sodium ion with larger guanidinium ion in 2-sulfonatofuryl nitronyl nitroxide yields weaker interlayer antiferromagnetic interaction.