MATRIX-ISOLATION OF A TRIPLET BIRADICAL FROM A CARBENE PRECURSOR

Low temperature ESR spectroscopy has been used to determine the geometry,1 spin distribution,2 ground-state multiplicity,3 and dynamical properties4 of thermally accessible triplet biradicals immobilized in solid solution. The biradical is usually prepared by direct photofragmentation of a cyclic azo or carbonyl compound. The success of the method is dependent upon the synthetic availability of the precursor and a finite quantum yield for formation of the triplet biradical. Even if the triplet is the ground state of the biradical, and it lies in a potential minimum, there may be no pathway for populating and observing it by ESR. © 1979, American Chemical Society. All rights reserved.