Encounter geometry determines product characteristics of electron transfer from 4-hydroxythiophenol to n-butyl chloride radical cations

The electron transfer reaction between the n-butyl chloride parent ion and if-thiophenol was studied using pulse radiolysis in solutions of 4-thiophenol in n-butyl chloride. It was found to have a diffusion-controlled rate constant of 1.5 X 10(10) dm(3) mol(-1) s(-1) and to involve contributions from all functional groups, i.e. -SH, -OH and the aromatic ring. Consequently, thiyl and phenoxyl radicals and 4-hydroxythiophenol radical cations were observed as direct products of this ion-molecule reaction. This unexpected reaction behavior could be explained by the hypothesis that the encounter geometry of the reaction partners determines the product characteristics. (C) 1999 Elsevier Science B.V. All rights reserved.