Structure, stability, and aromaticity of MSubPc (MB, Al, and Ga): Computational study

Abstract

AbstractA theoretical investigation on the structure, stability, and aromaticity of M‐subphthalocyanine (MSubPc; MB, Al, and Ga) was performed at the B3LYP/6‐31+G*//B3LYP/6‐31G* level. The comparison between MSubPc and the corresponding Mphthalocyanine (MPc) was considered. The geometry optimization of the MSubPc shows that in the AlSubPc and GaSubPc, the steric repulsions among the three azacoupled isoindole moieties increase, as to their macrocycles tend to be far from planarity. The binding energies of ClM … aza‐coupled isoindole corrected by the basis set superposition error (BSSE), and the nucleus‐independent chemical shift (NICS) values at the ring center, which are a simple and effective local aromaticity probe, were calculated. The results show that AlSubPc is less stable than both BSubPc and AlPc for larger steric repulsion, smaller binding energy, and weaker aromaticity. In the same way, GaSubPc is less stable than both BSubPc and GaPc. In addition, the ring expansion reactivity occurring in BSubPc was confirmed by the global aromaticity mirrored by the electrophilicity index ω values. Therefore, the AlSubPc and GaSubPc remain unknown, while the corresponding compounds AlPc and GaPc are known experimentally. © 2005 Wiley Periodicals, Inc. Int J Quantum Chem, 2005