Please use this identifier to cite or link to this item: http://localhost:8080/xmlui/handle/123456789/3544
Title: Electrostatic Topographical Viewpoint of π-Conjugation and Aromaticity of Hydrocarbons
Authors: Anjalikrishna, P K
Suresh, C H
Gadre, S R
Keywords: Aromaticity
Issue Date: 24-Oct-2019
Publisher: American Chemical Society
Citation: Journal of Physical Chemistry A;123(46):10139-10151
Abstract: A molecular electrostatic potential (MESP) topographical study has been conducted for a variety of conjugated hydrocarbons at B3LYP/6-311+G(d,p) level of theory to understand their π-conjugation features and aromaticity. The value of MESP minimum (Vm) is related to the localized and delocalized distribution of π-electron density. The Vm values are located interior to the rings in polycyclic benzenoid hydrocarbons (PBHs), whereas they lie outside the boundary of the rings in antiaromatic and in fused systems consisting of aromatic and antiaromatic moieties. The Vm points lie on top and bottom of the π-regions in linear polyenes and annulenes, while a degenerate distribution of CPs around the midpoint region of triple bonds is observed in alkynes. The eigenvalues λ1, λ2, and λ3 of the Hessian matrix at Vm(MESP minima) are used to define the aromatic character of the cyclic structures. The eigenvalues follow the trend λ1 ≫ λ2 > λ3 ≅ 0 in PBHs, λ1 > λ2 > λ3 ≅ 0 in linear polyenes, and λ1 > λ2 > λ3 ≠ 0 in antiaromatic systems. The difference in the aromatic character of PBHs from that of benzene is related to the deviations Δλ1, Δλ2, and Δλ3. The total deviation ∑i=13Δλi is found to be ≤ 0.011 au for all aromatic systems and lies between 0.011 and 0.035 au for all nonaromatic systems. For antiaromatic systems, its value is found to be above 0.035 au. Further, ∑i=13Δλi gives a direct interpretation of Clar’s aromatic sextet structures for PBHs. In summary, MESP topography mapping is a powerful technique to quantify the localized and delocalized π-electron distribution in a variety of unsaturated hydrocarbon systems.
Appears in Collections:2019

Files in This Item:
File Description SizeFormat 
Electrostatic Topographical Viewpoint_CH Suresh_Journal of PhysicalChemistryA.pdf
  Restricted Access
3.01 MBAdobe PDFView/Open Request a copy

Items in DSpace are protected by copyright, with all rights reserved, unless otherwise indicated.