Calculation of 14N and 35Cl quadrupole coupling constants on optimized molecular structures of pyrimidine, 2-X- and 5-X-pyrimidine, with X=F, Cl, Br, and CN Original Research Article

Abstract 14N(1,3) quadrupole coupling constants (nqccʹs) were calculated on B3P86/6-31G(3d,3p) optimized molecular structures of pyrimidine (PRM), 2-X-PRM, and 5-X-PRM, with X=F, Cl, Br, and CN. For PRM, the root mean square difference between calculated and experimental nqccʹs is 6 kHz (0.3%). For 2-F-PRM, the calculated value of −5.254 MHz for (χbb−χcc) lies within the rather large uncertainty (≈1%) in the experimental value. Hyperfine structure due to χaa was unresolved – its calculated value is −0.062 MHz. In the remaining molecules, for which no experimental data are available, nitrogen nqccʹs are predicted. In the Cl-PRMs, 35Cl nqccʹs are predicted. In the halogen substituted PRMs, differences in nqccʹs correlate with differences in carbon–halogen bond lengths.