35Cl AND 37Cl MAGNETIC RESONANCE OF SIMPLE CHLORINE COMPOUNDS

Abstract

The nuclear magnetic resonances of 35Cl and 37Cl in a number of simple chlorine compounds were measured. Since both the paramagnetic contribution for chemical shift and the quadrupole coupling constant of the atom are determined by the same radial distribution of the electron, a linear relationship between the chemical shifts and the quadrupole coupling constants may be expected for compounds for which the electronic excitation energies are comparable. This was demonstrated for the series of chloro-substituted methanes. By graphical extrapolation the absolute chemical shift of the reference compound, NaCl aqueous solution, was obtained. The chemical shift of Cl− aq. ion can be interpreted as the sum of the diamagnetic shift of Cl− spherical ion and a paramagnetic shift resulting from its hydration. The experimental and theoretical values of the paramagnetic chemical shift of the Cl2 molecule were −2.06 × 10−3 and −2.17 × 10−3, respectively. Paramagnetic chemical shifts and line widths of resonance spectra of simple chlorine compounds are discussed, as well as the feasibility of high-resolution chlorine resonances for structural applications.