Discrete ionization of two different short-living conformers of selenophenol by rapid free electron transfer to solvent parent radical cations

In the pulse radiolysis of solutions of selenophenol in n-butyl chloride, selenophenol radical cations and phenyl-selenyl radicals are generated as direct products of the ion-molecule reaction between the solvent parent radical cations and selenophenol. This effect is explained with an electron-transfer phenomenon where in each encounter situation the electron jump proceeds so extremely rapid that different transient conformers of the scavenger molecule must be taken into account, differing in the phases of the molecular torsion vibration of the C-SeH bond. Quantum-chemical calculations resulted in a very low activation energy of less than 1 kcal mol(-1) for the rotation of this bond and a favored geometry where the Se-H group is twisted against the aromatic moiety by an angle of 90degrees. (C) 2001 Elsevier Science B.V. All rights reserved.