Solution structure of 2-[(dimethylamino)methyl]phenyllithium

o-(Dimethylaminomethyl)phenyllithium (1a) forms three isomeric chelated dimers in THF-Me2O solution. In contrast to earlier reports that chelation in toluene solution was disrupted by stoichiometric amounts of THF, we find that chelation between the dimethylamino groups and the lithium is fully maintaine din solvents containing 50% by volume THF. Furthermore, neither TMEDA, PMDTA, nor HMPA breaks the chelation, although the latter does largely deaggregate the dimer, to form the bis-HMPA complex 5. Both the thermodynamic stability (monomer-dimer equilibrium constant) and kinetic stability (rat of dissociation) of the dimer 1a is higher than those of phenyllithium.