Theoretical predictions on structures and p-, s-orbital aromaticities of the Hg3B3+/−/3−, Hg3B3X (X = Li, Na, and K) and Hg3B3Mg+ clusters.

The structures, stabilities and chemical bonding in the mercuric low-borides Hg 3 B 3 +/−/3− clusters are investigated using density functional theory (DFT) calculations. The extensive search for the global minimum structures of Hg 3 B 3 +/−/3− at the DFT/B3LYP level of theory revealed that the ground-state for the Hg 3 B 3 + cation is a singlet state 1 A 1 ′ with the D 3h symmetry, the ground-state for the Hg 3 B 3 − anion is a singlet state 1 A 1 with the C 2v symmetry, and the ground-state for the Hg 3 B 3 3− cluster is a triplet state 3 B 2 with the C 2v symmetry. A detailed molecular orbital (MO) analysis reveals that the Hg 3 B 3 + (D 3h , 1 A 1 ′) cation possesses the double σ - ( σ t and σ r ) aromaticity, which is responsible for a planar regular hexagonal structure D 3h ( 1 A 1 ′) of Hg 3 B 3 + and perfect triangular Hg 3 framework, respectively. The Hg 3 B 3 − (C 2v , 1 A 1 ) anion possesses the multiple ( σ - and π-) aromaticity, which is responsible for a planar regular hexagonal structure C 2v ( 1 A 1 ) of Hg 3 B 3 − and the Hg 3 B 3 3− (C 2v , 3 B 2 ) anion possesses also the multiple ( σ- and π-) aromaticity, which is responsible for a planar regular hexagonal structure C 2v ( 3 B 2 ) of Hg 3 B 3 3− and perfect triangular Hg 3 framework, respectively. We search the hexagonal pyramidal-type Hg 3 B 3 X (X = Li, Na and K) and Hg 3 B 3 Mg + complexes, which containing Hg 3 B 3 − (C 2v , 1 A 1 ) ligand to reveal that Hg 3 B 3 − (C 2v , 1 A 1 ) structural unit was preserved preferably in Hg 3 B 3 X (C 3v , 5 A 2 ) (X = Li, Na and K) and Hg 3 B 3 Mg + (C 3v , 5 A 2 ) complexes. [ABSTRACT FROM AUTHOR]