QUANTUM-CHEMICAL INVESTIGATION OF THE ELECTRIC-FIELD EFFECT ON ACTIVATION BARRIERS FOR ELECTROCHEMICAL TRANSFORMATIONS OF ORGANIC-COMPOUNDS

The MINDO/3 method was used to study the effect of intensity and vecto r direction of the external electric field on activation barriers of u nimolecular reactions which are possible in electrochemical transforma tions of simple organic compounds: orientation of molecules and radica l anions, heterogeneous electron transfer to adsorbed molecules, disso ciation of radical anions, cations, and molecules, inversion of anions , free radicals, and neutral molecules, cis-trans isomerization, and c hair-boat conformational transition in molecules. The electronic and s patial structure of the molecules, free radicals, and ions, the height of the activation barriers of their reorientation, dissociation, isom erization, and conformational transition, and the configurational stab ility to change as affected by the field in the range 0.01-0.05 au are determined. Obtained data permit one to theoretically ground differen t effects under organic compound adsorption on the electrode surface, changes in stereochemistry of the products of alkyl halide electroredu ction, and some properties of chemically modified electrodes possibly affected by electrode potential gradient.