An insight on the aromatic changes in closed shell icosagen, tetrel, and pnictogen phenalenyl derivatives

Abstract

A computational study of the aromatic and antiaromatic characteristics of closed shell charged phenalenyl (PLY and PLY) upon replacement of the central carbon atom by icosagen (B, Al and Ga), tetrel (Si and Ge) and pnictogen (N, P and As) atoms comprising systems in which the icosagen and pnictogen derivatives considered are neutral while the tetrel ones are anions or cations, has been carried out at the B3LYP/6–311++G(d,p) computational level. By substitution, two different kinds of structures have been obtained, one planar (N and B) and another one bowl-shaped depending on the size of the central atom. In terms of aromaticity, the substitution of the central C atom causes a loss of the aromatic character in all cases as indicated by nucleus-independent chemical shifts (NICS) profiles and NICS values on the 0.001 au isosurface. Regarding the charge, PLY presents larger electron delocalisation than PLY, phenomenon associated with aromaticity. Furthermore, the current density maps for those planar systems corroborate NICS findings, showing anticlockwise currents in PLY (like in benzene) but clockwise in PLY-N and PLY-B, indicating aromatic and antiaromatic behaviour, respectively.