Singlet/Triplet State Anti/Aromaticity of CyclopentadienylCation: Sensitivity to Substituent Effect

It is well known that singlet state aromaticity quite insensitive to substituent effects, in the case of monosubstitution. In this work, we use density functional theory (DFT) calculations examine sensitivity triplet effects. For purpose, chose antiaromatic cyclopentadienyl cation, antiaromaticity which reverses aromaticity, conforming Baird’s rule. The extent (anti)aromaticity was evaluated by using structural (HOMA), magnetic (NICS), energetic (ISE), and electronic (EDDBp) criteria. We find monosubstituted cations weaker than benzene is, thus, slightly more sensitive As an addition existing literature data, also discuss effects on cation.