The equilibrium geometries of the cylinder-like lithium hydrocarbon complexes Li[C n ] 1 (n ϭ 7-12) are calculated within density functional theory with PBE0 exchange-correlation potential. The 6-31 G* basis was set on carbon and lithium atoms while STO-3G one was chosen for hydrogens. The complexes with odd n possess C s symmetry for equilibrium structures, and lithium is located near the border ofelectron system of the hydrocarbons. For complexes Li[C n ] 1 with even n (n ϭ 8, 10, 12), the lithium position at the center of benzene ring is stable, and the equilibrium geometry has C 2v point symmetry. We have observed correlation between the alternation of the equilibrium structure of the complex and degeneracy of boundary MO of isolated hydrocarbons. By using C nh symmetry, the -MO of the [C n ] 1 are found analytically within Huckel model. The nonbonding orbitals with energy ␣ take place only for hydrocarbons with even n. These MO's are characterized by the density distributions among the terminal carbon atoms with sign alternation of AO's contributions. The solution with energy ␣ with analogous distributions is present for larger hydrocarbons [C n ] q with any finite q and even n. FIGURE 3. The structures of lithium complexes Li[C n ] 1 for different n: (a) Li[C 10 ] 1, (b) Li[C 11 ] 1 . FIGURE A1. A structure fragment of the single bracelet [C n ] 1 . The unique atoms are selected and numbered. BALASHOV AND ERMILOV
The equilibrium geometries of the cylinder-like lithium hydrocarbon complexes Li[C n ] 1 (n ϭ 7-12) are calculated within Density Functional Theory(DFT) with PBE0 exchange-correlation potential. The 6-31 G* basis was set on carbon and lithium atoms while STO-3G one was chosen for hydrogens. The tendencies found for complexes with n ϭ 7-12 gets broken and transforms to asymptotic behavior in range of n Ͼ 13. The large complexes possess the structure where lithium is placed at the carbon hexagon center area and close to C 2v symmetry. Opposite, for n ϭ 5-6 lithium is placed on the high symmetry axis of initial hydrocarbon. Several stationary points of complexes with n ϭ 8 -21, defined by lithium location under the hexagon center (1), under the COC bond center (2) and at the hydrocarbon skeleton center (3) were found. The migration barriers between stationary points (1)-(3) were estimated. The type (3) structures are distinctly higher of energy than (1) and (2), at that the difference is increased according to growing of n. The complexes with n Ͻ 13 are characterized by usual charge transfer from metal to hydrocarbon skeleton, for n Ն 13 the molecular-like solution is occurred.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.