Synthesis of Nitroxide Diradical Using a New Approach.

A new synthetic pathway to diradical organic systems is proposed. The effectiveness of this approach was exemplified by the synthesis of a new nitroxide diradical. An interaction of perfluorobiphenyl with lithium -butylamide, followed by oxidation of the thusly formed 4,4'-di--butyl-2,2',3,3',5,5',6,6'-octafluorobiphenyl-4,4'-diamine with -chloroperoxybenzoic acid, led to the polyfluorinated nitroxide diradical, ,'-(perfluorobiphenyl-4,4'-diyl)bis(--butyl(oxyl)amine), with a good total yield. The polyfluorinated diradical is stable and can be isolated in free form and completely characterized. The structure of the nitroxide diradical was proved by single-crystal X-ray diffraction analysis. According to the X-ray diffraction data, the diradical is considerably twisted: dihedral angles between the planes of the nitroxide groups and aromatic cycles are 65.1° and 69.5°, and between aromatic cycles 52.6°. Quantum chemical calculations predict well-balanced size of both intramolecular and intermolecular exchange interactions with from -2.65 to -1.14 cm.