SYNTHESIS AND CHARACTERIZATION OF A NITROXIDE-SEMIQUINONE BIRADICAL

The synthesis and characterization of an anion biradical, 1(-..), comp osed of semiquinone and nitroxide functionalities is described. The bi radical was prepared by reduction of the nitroxide-orthoquinone precur sor using both electrochemical and chemical methods. The zero-field-sp litting parameter, \D/hc\, for 1(-..) is consistent with the proposed electronic structure, based on a comparison to \D/hc\ of related birad icals. Finally, the results of variable-temperature EPR spectroscopy a re in agreement with ferromagnetic thigh-spin) coupling of the two unp aired electrons through the m-phenylene group.