Specific Features of the Intramolecular Spin Exchange in a Novel Nitroxide Triradical

An X-band EPR spectroscopic study was performed of the temperature dependence of the dynamics of the intramolecular electron spin exchange in a triradical where the radical rings are linked by acetylene groups –C≡C–. A thermodynamic characteristic was determined for the conformational transition in the triradical between conformers where the spin exchange is of the triradical or biradical type. The geometric structure of the novel stable nitroxide triradical was determined using density functional theory calculations.