How does methyllithium invert? A density functional study

Quantum chemical studies (B3LYP) of the inversion of methyllithium in both tetrameric and dimeric aggregates have been carried out. Results show that inversion occurs either via dissociation of the tetramer into the dimers, p assage of a four-membered-ring transition state, and association of the dim ers to form the inverted tetramer, or via a nonconcerted route involving an eight-membered-ring transition state. The activation energies of these two mechanisms are similar. However, the dissociative mechanism is ruled out b y NMR experiments.