Multinuclear NMR spectroscopic studies at low temperature (-110 to -150 degrees C) revealed that lithium p-fluorophenolate and the lithium enolates of cyclohexanone, cyclopentanone and 4-fluoroacetophenone have tetrameric structures in THF/Et2O and THF/Et2O-HMPA by study of the effects of the addition of HMPA. The Z and E isomers of the lithium enolate of 1,3-bis-(4-fluorophenyl)-2-propanone (5F-Li) show divergent behavior. The Z isomer is completely dimeric in. pure diethyl ether, and mostly dimeric in 3:2 THF/ether, where monomer could be detected in small amounts. TMTAN and P, MDTA convert Z-5F-Li to a monomeric amine complex, and HMPA converts it partially to m, and partially to lithiate species (RO)(2)Li- and (RO)(3)Li2-. Better characterized solutions of these lithiates were prepared by addition of phosphazenium enolates (using P4-Bu-t base) to the lithium enolate in 1:1 ratio to form triple ion (RO)(2)Li(-)P4H(+), or 2:1 ratio to form the higher lithiate (RO)(3)Li2- (P4H(+))(2)) (quadruple ions). The E isomer of 5F-Li is also dimeric in 3:2 THF/Et2O solution, but is not delectably converted to monomer either by PMDTA or HMPA. In contrast to Z-5F-Li, the E isomer is tetrameric in diethyl ether even in the presence of excess HMPA. Thus for the two isomers of 5F six different enolate structures were characterized: tetramer, dimer, CIP-monomer, SIP-monomer, triple ion, and quadruple ion.