Charge Transfer Properties of dl -Thioctic Acid and Other Disulphides

THE ability of organic sulphur compounds to act as donors with electron acceptor molecules is well established. As far as disulphides are concerned, previous studies have been limited to simple aliphatic compounds with iodine as the acceptor 1 . In these systems, the charge transfer (CT) band appears between the disulphide absorption and the blue-shifted iodine absorption, and its position appears to be little affected by changing the alkyl groups. We wish to report that alkyl aryl and cyclic disulphides form 1 : 1 complexes in solution with tetracyanoethylene (TCNE), which show well-separated CT bands in the visible region. Further, the position of these bands clearly reflects steric and electronic factors in the disulphide molecule.