DISSOCIATIVE ELECTRON-TRANSFER - NEW TESTS OF THE THEORY IN THE ELECTROCHEMICAL AND HOMOGENEOUS REDUCTION OF ALKYL-HALIDES

In the testing of the theory of dissociative electron transfer with experimental data pertaining to the electrochemical and homogeneous reduction of alkyl halides, uncertainties arising from the estimation of the effect of solvent dynamics and reorganisation as well as of the resonance energy in the transition state are minimized by a comparative strategy which utilizes information derived from outer-sphere electron-transfer data gathered in the same solvent. Application of this strategy leads to a good agreement between theory and experiment in the electrochemical case. In the homogeneous case, the agreement is equally satisfactory in the case of tertiary halides. With the less sterically hindered secondary and primary halides, the reaction possesses an S(N)2 character involving small bonded interactions in the transition state in accord with previous stereochemical results and reaction entropy determinations.