Diagnosis of the σ-, π- and σ π-Aromaticity by the Shape of the NICSzz-Scan Curves and Symmetry-Based Selection RulesReport as inadecuate




Diagnosis of the σ-, π- and σ π-Aromaticity by the Shape of the NICSzz-Scan Curves and Symmetry-Based Selection Rules - Download this document for free, or read online. Document in PDF available to download.

1

Laboratory of Inorganic and General Chemistry, Department of Chemistry, University of Ioannina, 451 10 Ioannina, Greece

2

Laboratory of Applied Quantum Chemistry, Faculty of Chemistry, Aristotle University of Thessaloniki, 541 24 Thessaloniki, Greece





*

Author to whom correspondence should be addressed.



Abstract The NICSzz-scan curves of aromatic organic, inorganic and -all-metal- molecules in conjunction with symmetry-based selection rules provide efficient diagnostic tools of the σ-, π- and-or double σ + π-aromaticity. The NICSzz-scan curves of σ-aromatic molecules are symmetric around the z-axis, having half-band widths approximately less than 3 Å with the induced diatropic ring current arising from Tx,y-allowed transitions involving exclusively σ-type molecular orbitals. Broad NICSzz-scan curves half-band width approximately higher than 3 Å characterize double σ + π-aromaticity, the chief contribution to the induced diatropic ring current arising from Tx,y-allowed transitions involving both σ- and π-type molecular orbitals. NICSzz-scan curves exhibiting two maxima at a certain distance above and below the molecular plane are typical for σ + π-aromatics where the π-diatropic ring current overwhelms the σ-type one. In the absence of any contribution from the σ-diatropic ring current, the NICSzz0 value is close to zero and the molecule exhibits pure π-aromaticity.

Keywords: aromaticity; delocalization; σ-; π-; σ+π-aromaticity; NICSzz-scan; density functional theory DFT aromaticity; delocalization; σ-; π-; σ+π-aromaticity; NICSzz-scan; density functional theory DFT





Author: Athanassios C. Tsipis 1,* , Ioannis G. Depastas 2 and Constantinos A. Tsipis 2

Source: http://mdpi.com/



DOWNLOAD PDF




Related documents