Knowledge Bank

Pyrimidine, pyrimidine-2-$d1$, pyrimidine-2,5-$d2$, pyrimidine-4,6-$d2$, pyrimidine-2,4,6-$d3$ and pyrimidine-$d4$ were prepared from the corresponding chloropyrimidines by catalytic dehalogenation with deuterium gas. Isotopic contaminants were estimated by mass spectrometry. The Raman spectrum in the liquid phase and the infrared spectrum in both the vapor and liquid phases are reported for the above specifically labeled, partially deuterium-substituted, $C2v$ pyrimidine species. Based on the state of polarization of the Raman lines, the absence of $A2$ symmetry species in the infrared spectrum, and the band envelopes of the infrared vapor spectrum, an assignment is given which satisfies the Teller-Redlich product rule. Several instances in which the frequency sum rule is satisfied are also displayed. A set of independent force constants and a set of symmetry force constants are adjusted to fit the observed frequencies. The mean amplitudes of vibration, the Cartesian displacements for each normal mode and the Coriolis coefficients are computed.