C2V or C6V: Which is the most stable structure of the benzene–lithium complex?

The benzene–lithium complex is a prototype system to understand the interaction in lithium-doped nanocarbons. Herein, we have employed coupled-cluster theory and correlation consistent basis sets to study the C6v and C2v structures, of the C6H6·Li complex. We found that when the CCSD(T) method and large basis sets are employed, the C2V structure becomes lower in energy by 1.8 kcal/mol. At the CCSD(T)/CBS level, and including corrections for core–valence and relativistic effects, the dissociation energy of the C2v (ionic) structure is 6.7 kcal/mol whereas that corresponding to the C6v (nonionic) one is 4.9 kcal/mol. Our results suggest that charge transfer in C6H6·Li does exist, in contrast with previous results.