SOLVENT AND TEMPERATURE STUDIES OF SOME INDENYL-LITHIUMS AND FLUORENYL-LITHIUMS USING C-13 NMR-SPECTROSCOPY

13C NMR spectra of indenyl‐ and fluorenyllithium and some of their methyl substituted derivatives have been obtained. The shielding differentials induced by varying the temperature or coordinating ability of the solvent are discussed in terms of an equilibrium between discrete ion pairs or differences in external solvation. An increase of the coordinating ability of the solvent induces shift differentials of similar signs as those given by lowering the temperature. Methyl substituents close to the cation location are found to have only a minor effect on the observed ion pair ratio but seem to influence the preferred cation position in the tight ion pair structure. Copyright © 1979 Heyden & Son Ltd.