On the relations between aromaticity and substituent effect

摘要: Aromaticity/aromatic and substituent/substituent effects belong to the most commonly used terms in organic chemistry related fields. The quantitative description of aromaticity is based on energetic, geometric (e.g., HOMA), magnetic NICS) reactivity criteria, as well properties electronic structure FLU). substituent effect can be described using either traditional Hammett-type constants or characteristics quantum-chemistry. For this purpose, energies properly designed homodesmotic reactions electron density distribution are used. In first case, a descriptor named SESE (energy stabilizing effect) obtained, while second case cSAR (charge active region), which sum charge ipso carbon atom substituent. use above-mentioned allows revealing relationship between them for mono-, di-, polysubstituted π-electron systems, including substituted heterocyclic rings quasi-aromatic ones. It has been shown that less aromatic system, stronger influence its structure. all cases, when changes number π-electrons ring direction 4N+2, increases. Intramolecular transfer (a resonance privileged cases where bonds electron-attracting electron-donating atoms even. Quasi-aromatic rings, attached truly hydrocarbon, simulate “original” alike benzene. larger long-distance found.