Charge-transfer complexes: the interactions between tetracyanoethylene and aromatic amines

Charge-transfer complexes between tetracyanoethylene (TCNE) and a number of aromatic amines have been studied in dichloromethane solution. Correlations between transition energies and base strength of the amine or Hammett σ-function for substituents have been noted. Spectroscopic evidence as to the intermediacy of a σ-complex in the reaction between N-methylaniline and TCNE is cited and the presence of the tetracyanoethylene radical anion in the system reported.