Structural Dependence of Magnetic Shielding Properties in Al₄Li₄ Clusters

Abstract

This work demonstrates that the binding of Li atom plays an important role in the Al₄Li₄ clusters, which changes the structure of the Al₄ ring and induces the distinct magnetic shielding properties depending on the position of Li atom. The Al₄Li₄ cluster possesses both aromatic (S type) and antiaromatic (L type) isomers depending on the position of Li atom with an 8.74 kcal/mol energy difference at the singlet state. The bond length alternation (BLA) values and nucleus independent chemical shift analysis of each canonical molecular orbital (NICS-CMO) analyses show that S type isomers are aromatic and L type isomers are antiaromatic as the singlet low-lying states. A cyclic reaction pathway between L and S type isomers is mapped with five low-lying and five transition states including two intermediate states.