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

Abstract

Seven redox stages, the dication 12+, the radical cation , the neutral 1, the radical anion , the dianion 12-, the radical trianion , 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 and , 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 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 , , , as well as for radical ions of suitable reference compounds.