Substituent effects in fluoren-9-one ketyls. Part 3. An electron spin resonance, ENDOR, and TRIPLE resonance study of sodium ketyl solutions in tetrahydrofuran

Abstract

A series of ten fluoren-9-ones substituted in positions 2 or 3 or disubstituted in positions 2 and 7 and unsubstituted fluorenone was reduced by sodium in THF. E.s.r., ENDOR, special TRIPLE, and general TRIPLE resonance spectra of the respective sodium ketyls were recorded in the range 170–300 K and evaluated. The coupling constants thus obtained were used to study the effect of the substituents on electron spin distribution within the radical-anions and spin delocalization to the sodium ion. Linear correlations for the sodium couplings as a function of Hammett's substituent constants were found and discussed in terms of a static ion pair structure.