Determination of molecular geometry, rotational diffusion constants and coupling constants between quadrupolar nuclei and protons by means of proton N.M.R.

Expressions are given for the longitudinal and transverse relaxation rates of the individual lines in a HRNMR proton AX2 spectrum. The relaxation mechanisms considered are dipolar and scalar interactions. Measurements are performed on the proton spectra of dilute degassed solutions of 2-amino pyrimidine in acetone-d6/D2O. The relative values are determined of the interproton distances in the AX2 system and of three rotational diffusion constants, Dxx , Dyy and Dzz . Two coupling constants between the ring protons and the 14N ring nitrogens are found to be 10·3 and 2·2 Hz.