Alkali N.M.R. experiments on the radical ion pairs of biphenyl and fluorenone

Abstract

Results of ⁶Li, ⁷Li, ²³Na, ³⁹K, ⁸⁵Rb, ⁸⁷Rb and ¹³³Cs N.M.R. experiments on solutions of the alkali salts of biphenyl and fluorenone in various ethers are presented. The contributions of the Fermi contact interaction and the chemical shielding to the shift of the N.M.R. signal are discussed. Sign and magnitude of the alkali hyperfine splitting constants are derived from the experimentally measured shifts and their variation with temperature and solvent are analysed.