Electron spin exchange in rigid biradicals

Abstract

Eleven rigid nitroxyl biradicals have been synthesized vJith distances between the radical groups of up to 12 t The electron spin resonance spectra were studied in a variety of solvents and over a range of temperatures.S-resonances, \,/hi ch permi t the electron exchange i nteracti on (~) to be determi ned \,/ith preci s i on, were observed for all but one of the biradicals.Spectra corresponding to J = 6 G up to J = --172 G were obtained.The effects of structure on the exchange are com-