Synthesis of nitroxide diradical using a new approach

Abstract

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 tert-butylamide, followed by oxidation of the thusly formed N4,N40di-tert-butyl-2,20,3,30,5,50,6,60-octafluorobiphenyl-4,40-diamine with meta- chloroperoxybenzoic acid, led to the polyfluorinated nitroxide diradical, N,N0-(perfluorobiphenyl-4,40-diyl)bis(Ntert-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 J from −2.65 to −1.14 cm−1