Abstract The nature of carbon-lithium bonding in benzyllithium and 1,1-diphenyl-n-hexyllithium and its variation with solvent is evaluated from carbon, lithium, and proton nuclear magnetic resonance measurements. The solvent dependency of the NMR data is interpreted as evidence that the α-carbons of these arylmethyllithiums have appreciable sp 3 character which increases with decreasing solvent polarity. Anion-cation interaction accordingly increases with decreasing solvent polarity. Solvent induced changes in ligand (anion-cation) interactions are considered to be the predominant factor influencing the nature of the carbon-lithium bonding. The larger π-system of 1,1-diphenyl-n-hexyllithium is suggested to moderate the dependence of anion-cation interaction on solvent and to result in greater (than in benzyllithium) sp 2 character to the α-carbon.