Paramagnetic Redox Stages of a Bisphane: An ESR and ENDOR Study

Seven redox stages, the dication 12+, the radical cation {article}{empty}{document}1^ +-4pt .-2pt{document} , the neutral 1, the radical anion {article}{empty}{document}1^ -4pt .-2pt{document} , the dianion 12−, the radical trianion {article}{empty}{document}1^ 3-4pt .-2pt{document}{document} , and the tetraanion 14−, are indicated by cyclic voltammetry for the bisphane 1, in which the benzene decks of two lateral paracyclophane moieties are orthogonal to the plane of anthracene framework. In {article}{empty}{document}1^ +-4pt .-2pt{document} and {article}{empty}{document}1^ -4pt .-2pt{document} , the unpaired electron is accommodated into the central anthracene subsystem, and the same statement holds for the two positive or negative charges in 12+ and 12−. Formation of {article}{empty}{document}1^ 3-4pt .-2pt{document}{document} and 1− occurs through admission of additional electrons one‐by‐one into the two paracyclophane moieties flanking the doubly charged anthracene subsystem in 12−. The above‐postulated, successive release or uptake of electrons by the individual parts of the bisphane is in perfect accord with the hyperfine data determined by ESR and ENDOR spectroscopy for {article}{empty}{document}1^ +-4pt .-2pt{document} , {article}{empty}{document}1^ -4pt .-2pt{document} , {article}{empty}{document}1^ 3-4pt .-2pt{document}{document} , as well as for radical ions of suitable reference compounds.