Computer Assignment Technique for Analysis of High-Resolution NMR Spectra

Abstract

A computer assignment technique for calculating chemical shifts and spin coupling constants from experimental high‐resolution proton magnetic resonance spectra is described. The observed spectral lines are assigned to transitions within the energy‐level diagram in a manner consistent with equal‐spacing and intensity‐sum rules. Experimental eigenvalues are calculated and introduced into equations derived from the spin Hamiltonian secular determinant in analytical form and in the diagonal experimentally observed form. These equations are implicit in the chemical shifts and spin coupling constants and in general must be solved by numerical methods although in some cases explicit solutions are found. The technique is applied to the 60 Mc spectrum of o‐dichlorobenzene to obtain the results δ=15.23 cps, J₁₂=8.17 cps, J₂₃=7.44 cps, J₁₃=1.61 cps, and J₁₄=0.36 cps.