Quantum Mechanical Analysis of High Resolution NMR-Spectra of Some Tri-Substituted Benzenes

Abstract

High Resolution NMR-Spectra (recorded at 90 MHz and 270 MHz) of
some three spin aromatic systems (ABC type), viz., 2,4-dichlorophenol and
3,4-dimethylphenol have been analysed quantum mechanically with the
help of second-order perturbation theory.
In both cases,  δ_ij /J_ij suggests the failure of first order rule. The analysis
of complex spectra was carried out with the help of successive iterations
and convergence of the J_ij's and  δ_ij's. With these converged values, intersities
of several spectral transitions were calculated and then used to draw
the theoretical stick-spectrum to compare them with experimental ones.