Vibrational analysis and spectra of orotic acid

The IR and Raman spectra of polycrystalline anhydrous orotic acid and its N 1, N3, and O12 trideuterated isotopomer are recorded in the 4000-40 cm(-1) spectral interval as part of a series of vibrational analyses of nucleoside s, nucleotides, and related compounds carried out in our laboratory. The fr equencies of the fundamental transitions and the potential energy distribut ions of the 39 normal modes of orotic acid and its isotopomer are calculate d by an ab initio density functional theory Becke3P86/6-311G** treatment. A ssignments of the vibrational modes are proposed that consider the results of these calculations and the observed spectra. The results of the ab initi o treatment are related to crystallographic and spectral data, and they are compared with previous assignments for similar molecules. (C) 2000 John Wi ley & Sons, Inc.