  Benzene (C6H6) and polycyclic hydrocarbons such as naphthalene (C10H8),
anthracene (C14H10) and coronene (C24H12) are well known aromatic organic
compounds. We study the substitution of Li replacing all H atoms in these
hydrocarbons using density functional method. The vertical ionization energy
(VIE) of such lithiated species, i.e., C6Li6, C10Li8, C14Li10 and C24Li12
ranges 4.24-4.50 eV, which is lower than the IE of Li atom. Thus, these species
may behave as superalkalis, due to their lower IE than alkali metal. However,
these lithiated species possess planar and closed-shell structure, unlike
typical superalkalis. Furthermore, all Li-substituted species are aromatic
although their degree of aromaticity is reduced as compared to corresponding
hydrocarbon analogues. We have further explored the structure of C6Li6 as
star-like, unlike its inorganic analogue B3N3Li6, which appears as fan-like
structure. We have also demonstrated that the interaction of C6Li6 with a
superhalogen (such as BF4) is similar to that of a typical superalkali (such as
OLi3). This may further suggest that the proposed lithiated species may form a
new class of closed-shell organic superalkalis with aromaticity.
