ELECTRONIC EFFECT OF THE CYCLOPENTADIENYL ANION AS A SUBSTITUENT. THE EFFECT OF THE ALKALI METAL CATION, SOLVENT AND COMPLEXING AGENTS ON 19F CHEMICAL SHIFTS OF m- AND p-FLUOROPHENYLCYCLOPENTADIENYL ANIONS

Article abstract of DOI:10.1016/S0022-328X(00)92606-8

Salts of the carbanions M^+-, where M = Li, Na, and K, have been investigated by 19F NMR spectroscopy.The effect of the alkali metal cation, the coordinating ability of the solvent, complexing agents (TMEDA, crown-ethers), and concentration on the 19F chemical shifts has been studied.The results are discussed in terms of an equilibrium between tight and solvent-separated ion pairs.On the basis of 19F chemical shift data for Li^+- in HMPA solution, the electronic effect of the C5H4^- substituent as a "free ion" has been determined.