Model study of the primary H/D isotope effects on the NMR chemical shift in strong hydrogen-bonded systems

The model of the OHO (ODO) quasisymmetric fragment potential energy surface suggested earlier is used for calculation of the H/D substitution effect on the chemical shift (δH or δD) of the bridged nucleus as function of the O-O equilibrium distance RH e (2.40 ≤ RH e ≤ 2.60 Å) for systems with a strong H bond. The theoretical curves are compared with the experimental data. The non-monotonous ΔδH/D=δH-δD dependence on RH e and on δH as well as the negative and large positive (0.2 ppm) ΔδH/D values are interpreted. © 1992.