Structures and aromaticity of the planar B 2XY (X = N, P and Y = O, S, Se) and Al 2MN (M = C, Si, Ge and N = S, Se) clusters

Abstract

Clusters B 2XY (X = N, P and Y = O, S, Se) and Al 2MN (M = C, Si, Ge and N = S, Se) species are theoretically investigated with density functional theory (DFT) method. The results show that although the most stable isomers for B 2XY and Al 2MN species have a similar structure, they show a different symmetry at the B3LYP/6-311+G* level. NICS analysis displays that both B 2XY and Al 2MN possess strongly aromatic character, and the atomic size has an important effect on the stability of stable planar structures for these species. In addition, the presence of two delocalized π electrons does agree well with the (4 n + 2) Huckel rule, which confirms that aromaticity plays an important role in the stability of planar structures for B 2XY and Al 2MN species. Moreover, MO analysis shows that the delocalized extent of π MO for the most stable B 2XY species is larger than that for the most stable Al 2MN species.