Quantification of Aromaticity of Heterocyclic Systems Using Interaction Coordinates

Area of Science:

• Quantum Chemistry
• Theoretical Chemistry
• Computational Chemistry

Background:

• Aromaticity is a key concept in chemistry, influencing molecular properties and reactivity.
• Existing aromaticity indices, like the aromaticity index based on interaction coordinates (AIBIC), perform well for hydrocarbons but struggle with heterocyclic systems.
• Heterocyclic systems exhibit localized electron density due to electronegativity differences, which can lead to overestimation of aromaticity by current indices.

Purpose of the Study:

• To develop a corrected aromaticity index that accurately assesses aromaticity in heterocyclic compounds.
• To address the overestimation of aromaticity observed with the AIBIC in systems containing heteroatoms.
• To provide a more reliable computational tool for evaluating aromaticity in diverse chemical structures.

Main Methods:

• Introduction of a correction factor into the AIBIC calculation based on Pauling's electronegativity equation.
• Computation of the corrected aromaticity index for various heterocyclic systems.
• Comparison of results with established chemical expectations for aromaticity.

Main Results:

• The corrected aromaticity index provides results consistent with theoretical expectations for heterocyclic systems.
• The new index successfully accounts for electron density localization caused by heteroatoms.
• The corrected index demonstrates improved accuracy in quantifying aromaticity compared to the original AIBIC for heterocycles.

Conclusions:

• The corrected aromaticity index based on interaction coordinates is a promising tool for accurately quantifying aromaticity in heterocyclic systems.
• This refined index overcomes limitations of previous methods by incorporating electronegativity corrections.
• The developed method offers enhanced reliability for computational studies involving aromaticity assessment.