Intermolecular π-bonding between cation-radicals and between radicals and their parent donors provides fascinating data for the development of fundamental concept of chemical bonding, and it is critical for the self-assembly and properties of their solid-state associates. The intrinsic ion-radical interactions, however, are commonly obscured by counter-ions and solvation. These external factors can be minimized via the application of the weakly-coordinating counter-ions, such as tetrakis[3,5-bis(trifluoromethyl)phenyl]borate, BArF, such as closo-dodecamethylcarboranate, CAR. In the current work, we prepared stable cation-radical salts of tetratiafulfalene derivatives and aromatic or antiaromatic hydrocarbons with these anions. It allowed to evaluate the role of solvent and counter-ions in the formation of the π-dimer of these cation-radicals, D+● D+● + D+● ↔ D22+ We also demonstrate that crystallization of the D+●CAR- salts in the presence of the neutral donors produced the mixed-valence 2D-layers resulting from the self-assembly of planar organic cation-radicals with their parent molecules which are separated by the CAR- counter-ions (Figure, left). Similar crystallization of the D+●BArF- salts afforded isolated one-dimensional arrays of π-stacked partially-oxidized donors located within the nanochannels formed by the bulky inert anions (Figure, right). Thus, these anions provide an opportunity to evaluate effects of dimensionality on the solid-state properties of the cation-radicals-salts. Structural criteria of formation of such π-bonded molecular wires vs isolated cation-radical moieties are discussed.

Intermolecular interactions and self-assembly of cation-radical salts with weakly-coordinating anions

256th National Meeting (2018)

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