ChemInform Abstract: SOLVATION EFFECTS ON THE ELECTRON-TRANSFER REACTION OF TCNQ ANION RADICAL AND 2,3-DICHLORO-5,6-DICYANO-P-BENZOQUINONE

Rate constants were obtained with a temperature-jump apparatus for the electron-transfer reaction between 7,7,8,8-tetracyanoquinodimethane anion radical and 2,3-dichloro-5,6-dicyano-p-benzoquinone in acetonitrile/ tetrahydrofuran (MeCN/THF) and in acetonitrile/water (MeCN/H2O) mixtures. In MeCN/THF, the forward rate constant (k) was determined in three kinds of mixed solvents: k=(5±2)×109 M−1s−1 (pure MeCN), (2.2±0.2)×109 M−1s−1 (1: 2 MeCN/THF), and (6±2)×108 M−1s−1 (1: 10 MeCN/THF) at 25±2°C. In MeCN/H2O the forward rate constant increases with the square of the H2O concentration in the range of [H2O]=2–10 M; k=k0[H2O]2 with k0=(1.0±0.2)×106 M−3s−1 at 25±2 °C. The results are discussed in terms of the specific solvation and the ion-pairing of ion radicals.