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Is Al2Cl6 aromatic? Cautions in superficial NICS interpretation
Juan José Torres1, Rafael Islas, Edison Osorio
1Departamento de Química, Facultad de Ciencias Exactas, Universidad Andres Bello , Av. República 252, Santiago, Chile.
The Journal of Physical Chemistry. A
|June 12, 2013
Summary
The Al2X6 clusters are not aromatic systems, contrary to potential interpretations of common chemical shift indices. Detailed analysis reveals superficial use of nucleus-independent chemical shift (NICS) can lead to incorrect conclusions in computational chemistry.
Area of Science:
- Quantum Chemistry
- Theoretical Chemistry
- Materials Science
Background:
- Aromaticity is a key concept in chemistry, influencing molecular stability and reactivity.
- The nucleus-independent chemical shift (NICS) is a widely used computational index to assess aromaticity.
- Aluminum-based clusters, such as Al2X6, are of interest for their unique electronic properties.
Purpose of the Study:
- To rigorously evaluate the aromatic character of Al2X6 (X = F, Cl, Br, I) clusters.
- To investigate the reliability of the nucleus-independent chemical shift (NICS) index for determining aromaticity in these systems.
- To provide a cautionary note on the interpretation of NICS values in computational chemistry.
Main Methods:
- Employment of the induced magnetic field method to probe electronic response.
- Detailed analysis of nucleus-independent chemical shift (NICS) values.
- Computational chemistry techniques to model Al2X6 clusters.
Main Results:
- The induced magnetic field method demonstrates that Al2X6 clusters lack aromatic characteristics.
- In-depth NICS analysis confirms the non-aromatic nature of these clusters.
- Superficial interpretation of NICS values can lead to erroneous conclusions regarding aromaticity.
Conclusions:
- Al2X6 clusters are definitively not aromatic systems.
- A detailed and critical approach to NICS index analysis is essential for accurate chemical interpretation.
- This study serves as a warning against oversimplified application of computational indices in chemistry.
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