Solvent-Shared and Solvent-Separated Ion Multiples of Perylene Radical Anions and Dianions: An Exemplary Case of Alkali Metal Cation Solvation

The hydrocarbon perylene (C 20 H 12 ) has been crystallized, and several of its radical anions and dianion salts have been prepared by reduction with various alkali metal mirrors under argon and aprotic conditions in different ether solvents. The single-crystal structures determined at low temperature are discussed in terms of single and double negative charge perturbation based on geometry-optimized density functional calculations at the B3LYP level with 6-31G* basis sets. All perylene radical anion salts [C 20 H 12 • - ][M + solv ] and [C 20 H 12 • - ···C 20 H 12 ][M + solv ] crystallize as solvent-separated ion pairs, whereas the structures of the perylene dianion salts [C 20 H 12 2 - (M + solv ) 2 ] or [C 20 H 12 2 - ][M + solv ] 2 strongly depend on the optimum solvation of the alkali metal countercations. The experimental results allow the rationalization of essential facets of the network of redox equilibria in solution.