Sodium and proton ENDOR and triple-resonance experiments on biphenyl and fluorenone ion pairs in solution

Abstract

ENDOR and triple-resonance spectra of fluorenone ketyl and biphenylide sodium ion pairs in ethereal solutions are reported. For the first time alkali metal cation resonance lines could be observed at frequencies below 4 MHz belonging to counterion hyperfine constants as small as 100 kHz. The temperature dependence of the hyperfine constants and their signs were determined by triple resonance and were compared with previous ESR and NMR results. This comparison shows that, for fluorenone, different ion pair structures occur in concentrated and diluted solutions.