Synthesis and Characterization of a Nitroxide-Semiquinone Biradical
David A. Shultz1, Gary T. Farmer
1Department of Chemistry, North Carolina State University, Raleigh, North Carolina 27695-8204.
Abstract:
The synthesis and characterization of an anion biradical, 1(-)(*)(*), composed of semiquinone and nitroxide functionalities is described. The biradical was prepared by reduction of the nitroxide-orthoquinone precursor using both electrochemical and chemical methods. The zero-field-splitting parameter, |D/hc|, for 1(-)(*)(*) is consistent with the proposed electronic structure, based on a comparison to |D/hc| of related biradicals. Finally, the results of variable-temperature EPR spectroscopy are in agreement with ferromagnetic (high-spin) coupling of the two unpaired electrons through the m-phenylene group.
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