Nitroxide radicals. Part X. Electron spin resonance spectra of [2,2]paracyclophanylene bisnitroxides

Abstract

Spectra of three [2,2]paracyclophanylene bisnitroxides have been measured. For two of the biradicals the exchange interaction J is much larger than the nitrogen hyperfine splitting and five-line e.s.r. spectra are observed, while for the third the zero-field splitting is so large that its solution spectrum cannot be resolved. Values of the zero-field tensor D for all three biradicals have been evaluated by measuring their spectra in glasses.