On the electronic structures and s/p-orbital aromaticity in the Hg3Al3+/−, Hg3Al3Li, and Hg3Al3Be+ clusters.

The equilibrium geometries, harmonic vibrational frequencies, stabilities, and chemical bonding of the low-lying states for all-metal Hg 3 Al 3 +/− , Hg 3 Al 3 Li, and Hg 3 Al 3 Be + clusters are investigated using 2nd order Møller–Plesset perturbation theory. The extensive search for the global minimum structures of Hg 3 Al 3 +/− at the MP2 level of theory with 6-311++G∗ basis set for Al and CEP-121 G basis set for Hg reveals that the ground states of the Hg 3 Al 3 + and Hg 3 Al 3 − clusters are all singlet state 1 A′ with C s symmetry. A detailed molecular orbital (MO) analysis reveals that the Hg 3 Al 3 + (C s , 1 A′) cation and Hg 3 Al 3 − (C s , 1 A′) anion possess double aromaticity (simultaneous presence of σ- and π-aromaticity). The hexagonal pyramidal-type Hg 3 Al 3 Li and Hg 3 Al 3 Be + complexes containing the Hg 3 Al 3 − ligand reveal that the Hg 3 Al 3 − structural units are preserved in the Hg 3 Al 3 Li and Hg 3 Al 3 Be + complexes, which also possess corresponding aromatic characters. [ABSTRACT FROM AUTHOR]