A quantitative analysis of the intermolecular forces responsible for the formation of aggregates/complexes involving organolithium compounds has been undertaken using the Restricted Variational Space (RVS) decomposition scheme of the intermolecular interaction energy.

Two series of RVS computations have been carried out for every complex. The first one concerns the fully optimized systems while for the second the optimization has been limited to the intermolecular parameters. As expected, our results confirm that the electrostatic contribution is always the main stabilising component in these systems even when one of the partners of the complex is non-polar. In the case of aggregation between two lithiated species, comparison of the two sets of results indicates that the distortion undergone by the partners in the complexes takes place at the expense of an energy decrease of the interacting entities which is minor when compared to the concomitant increase of the electrostatic contribution. In the case of methyllithium dimer we have checked that the extension of the basis set does not alter these results.