Abstract
The possibility of organic high-spin molecules based on the double-exchange (DE) mechanism has never been examined. In this work, we designed a tetraphenyl-para-phenylenediamine (1) having stable nitronyl nitroxides at all para-positions. Upon one-electron oxidation of the central phenylenediamine moiety, 1 is expected to be a novel organic high-spin molecule due to DE mechanism. The tetraradicals 1 was prepared by means of the following reactions. Diacylimidazolium ion, which is generated from imidazole and trifluoroacetic anhydride, yielded adducts with tetraphenyl-para-phenylenediamine. The adducts were hydrolyzed into the corresponding tetraaldehydes under mild conditions in high yield. The resulting tetraaldehydes were converted to 1 by the ordinary method. The ESR spectrum of 1 in CH2Cl2 at room temperature showed a complicated hyperfine structure, suggesting the presence of exchange coupling among four nitronyl nitroxide radical centers
