DISSOCIATIVE ELECTRON-TRANSFER TO POLYHALOGEN METHANES CY3X (Y=H, F, CL AND BR, X=CL AND BR) IN SOLVENT - A SEMIEMPIRICAL PM3 METHOD STUDY

The free energy curves for a carbon-chlorine and carbon-bromine bond i n polyhalogen methane radical anions in a solvent were calculated by t he semiempirical PM3 method. It was shown that the effect of solvation results in a noticeable change in the form of some gas phase curves. The anion states CH<INF>3</INF>Cl<SUP>-</SUP>., CH<INF>3</INF>Br<SUP>- </SUP>., CCl<INF>4</INF><SUP>-</SUP>.<SUP></SUP> are found to be unsta ble with respect to the breaking of the C-X bond in solvent, whereas o ther anion states are characterized by potential wells in these curves . Absolute potentials for the reactions CY<INF>3</INF>X(sol)+ e<SUP>-< /SUP>(gas) -->CY<INF>3</INF>(sol)+ X<SUP>-</SUP>(sol) are calculated a nd compared with the values obtained by Eberson with the use of a ther mochemical cycle procedure. (C) 1998 Elsevier Science S.A. All rights reserved.