| Article ID | Journal | Published Year | Pages | File Type |
|---|---|---|---|---|
| 1408850 | Journal of Molecular Structure | 2013 | 8 Pages |
The aromaticity of s-cis and s-trans pyrrol-2-yl carbonyl conformers was studied by FT-IR, 1H NMR spectroscopy and DFT calculations at the B3LYP/6-311++G(d,p) level of theory. The Harmonic Oscillator Model of Aromaticity (HOMA) and Nucleus Independent Chemical Shift (NICS) indices were calculated to estimate π-electron delocalization in the pyrrole ring. The usefulness of infrared spectroscopy in the evaluation of the aromaticity of the homogeneous set of pyrroles is discussed. The influence of 2-substitution on different aspects of aromaticity and stability of the pyrrol-2-yl carbonyl conformers is also discussed. It is concluded that the substitution effect of the title pyrrole derivatives can be explained on the basis of theoretical and experimental measurements of π-electron delocalization, including IR data.
Graphical abstractFigure optionsDownload full-size imageDownload as PowerPoint slideHighlights► Pyrrol-2-yl carbonyl conformers; IR, NMR. ► Density functional theory (DFT). ► Harmonic Oscillator Model of Aromaticity (HOMA). ► Nucleus Independent Chemical Shift (NICS). ► Experimental measures of π-electron delocalization.
