Abstract
We report a new antiferromagnetic radical-anion salt (RAS) formed from 7,7,8,8-tetracyanquinonedimethane (TCNQ) anion and 2-amino-5-chloro-pyridine cation with the composition of (N-CH(3)-2-NH(2)-5Cl-Py)(TCNQ)(CH(3)CN). The crystallographic data indicates the formation of (TCNQ)(2) (.-) radical-anion π-dimers in the synthesized RAS. Unrestricted density functional theory calculations show that the formed π-dimers characterize with strong π-stacking "pancake" interactions, resulting in high electronic coupling, enabling efficient charge transfer properties, but π-dimers cannot be stable in the isolated conditions as a result of strong Coulomb repulsions. In a crystal, where (TCNQ)(2) (.-) π-dimers bound in the endless chainlets via supramolecular bonds with (N-CH(3)-2-NH(2)-5-Cl-Py)(+) cations, the repulsion forces are screened, allowing for specific parallel π-stacking interactions and stable radical-anion dimers formation. Measurements of magnetic susceptibility and magnetization confirm antiferromagnetic properties of RAS, what is in line with the higher stability of ground singlet state of the radical-anion pair, calculated by means of the DFT. Therefore, the reported radical-anion (N-CH(3)-2-NH(2)-5Cl-Py)(TCNQ)(CH(3)CN) solvate has promising applications in novel magnetics with supramolecular structures.