Article ID: 1536 - Last Modified: July 12, 2011
Is there a way to tell if a ring is aromatic or not, using Jaguar?
Yes, you can do this by calculating the NMR shielding at the center of the ring, and compare it with known aromatic and nonaromatic compounds. The following procedure shows you how to calculate the shielding:
- Import the ring-containing structure into Maestro.
- Choose Edit → Centroids, to open the Centroids panel.
- Pick the atoms in the ring, and click Create Centroid Atom.
- Click Delete All. You can close the Centroids panel.
- Click the Create Entry button to create a new project entry.
- Run a Jaguar single point calculation (Applications → Jaguar → Single Point Energy) with NMR shielding constants selected in the Properties tab. The remaining settings can be left at the defaults.
- After the job finishes, you can obtain the value of the isotropic shielding either from the output file (.out), or by labeling the atoms in the Workspace with the NMR Shielding property (select this property in the Composition tab of the Atom Labels panel and label the atoms).
Repeat the above procedure for some reference aromatic and nonaromatic compounds, such as benzene, cyclopentadiene, cyclohexane. You can then compare the shielding value obtained for your query compound with the reference values to determine whether the query compound is aromatic (or how aromatic it is).
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