STUDIES ON THE CARBANIONS AFFECTED BY NEIGHBORING SULFUR GROUPS .1. EFFECT OF THE OXIDATION NUMBER OF SULFUR ATOM ON ION-PAIRING AND ELECTRON-TRANSFER OF THE ALKALI-METAL FLUORENYL CARBANIONS SUBSTITUTED IN 9 POSITION WITH PHENYL SULFUR GROUPS

Ion-pairing effects derived from the difference in oxidation number of the sulfur atom in the alkali metal fluorenyl carbanions substituted in 9 position with phenyl sulfur groups (PhSOn Fl-, M+; n = 0, 1, and 2) were reflected in the electronic absorption and 1H NMR spectra and also in the electron-transfer reactions. The solvent-separated PhSFl-∥M+ ion pairs in THF at 20 °C and the contact PhSOFr-,M+ ion pairs in MTHF even at 77 K were found. The alkali metal PhSO2Fl- carbanions exhibited the different type of electronic absorption band due to an intramolecular charge transfer. In NMR spectra the chemical shift of H18 protons also gave information about ion pairing in the carbanions. For the contact ion pairs electron transfer to anthraquinone (AQ) was more facile than for the solvent-separated ion pairs. Electron transfer from the solvent-separated AQ- ∙ ∥Li+ ion pair to PhSO2Fl- radical was also studied by means of flash photolysis (ktr = 7.6 X 109 M-1 s-1). © 1979, American Chemical Society. All rights reserved.