ACCURATE DETERMINATION OF SMALL SPLITTING CONSTANTS FOR ORGANIC RADICALS BY NMR

FT-NMR spectra of the radicals di-tert-butyl nitroxide (1) and glavinoxyl (2) are reported. Earlier CW NMR work using internal referencing gave inconsistent results for ESR splitting constants because the concentration dependence of the paramagnetic chemical shift DELTA-delta was unaccounted for. This technique is a viable alternative to ENDOR and uses standard NMR equipment.