STRUCTURE AND STABILITY OF 2-SIGMA/1-SIGMA STAR 3-ELECTRON-BONDED RADICAL CATIONS FROM 1,N-BIS(ALKYLTHIO)ALKANES IN AQUEOUS-SOLUTIONS

A large number of 1,n‐bis(alkylthio)alkanes, R′S(CH2)nSR″, was investigated by pulse radiolysis in aqueous solutions. The sulphur‐centred radical cations, which were obtained on oxidation of the dithia compounds by ·OH radicals, are stabilized via 2σ/1σ* three‐electron interaction between two sulphur atoms. Intramolecular stabilization is the only process observed for n = 2–4, whereas for longer chain compounds with n > 4 some intermolecular sulphur–sulphur interaction is also indicated. The stability and yields of the three‐electron‐bonded species also depend on the nature of the substituents R′ and R″, and for the intermolecular systems are a function of solute concentration. The results corroborate earlier investigations and demonstrate, in particular, that the optical parameters are a very sensitive measure of changes in electron density and structure of the three‐electron‐bonded systems. Copyright © 1990 John Wiley & Sons Ltd.