title: Radical Cations of Dithia- and Tetraselenaradialenes with Restricted Delocalization of the Unpaired Electron.
abstract: The radical cations of the permethylated dithia[6]radialene 1 and the tetraselena[8]radialene 2 have been investigated by ESR- and ENDOR-spectroscopy. It is shown that in the radical cation of 1 the unpaired electron is delocalized only in one half of the molecule. The magnitude of the (33)S coupling constant suggests a restricted localization within the 2,3-dithiatetramethyl-butadiene unit. We ascribe the slow electron transfer from one part of the molecule to the other to steric effects. The analysis of the ESR spectrum of 2(*)()(+)() shows that only two of the four selenium atoms are involved. The delocalization of the unpaired electron is restricted to only one of the divinyl diselenide moieties with a slow electron transfer rate to the other one.
authors.affiliation: Organisch-Chemisches Institut der Universität Heidelberg, Im Neuenheimer Feld 270, 69120 Heidelberg, Germany, and Abt. Organische Chemie, Max-Planck-Institut für medizinische Forschung, Jahnstrasse 29, 69120 Heidelberg, Germany.
authors.forename: Rolf
authors.initials: R
authors.lastname: Gleiter
authors.forename: Harald
authors.initials: H
authors.lastname: Röckel
authors.forename: Franz A.
authors.initials: FA
authors.lastname: Neugebauer