FT-IR SPECTROSCOPIC STUDY OF URACIL DERIVATIVES AND THEIR HYDROGEN-BONDED COMPLEXES WITH PROTON DONORS .2. MONOMER IR ABSORPTIONS OF THIOURACILS AND 5-HALOGENO-URACILS IN ARGON MATRICES

The matrix-isolation FT-IR spectra of 2-thio-, 1-methyl-2-thio-, 4-thio-, 5-bromo-, 5-fluoro- and 1-methyl-2-thio-5-bromo-uracil are investigated in Ar at 10 K. Detailed spectral analysis in comparison with uracil and methylated uracils, and with recent literature ab initio calculations for some of the studied derivatives allows the fundamental modes to be assigned. Some important modes are suitable probes for future investigations of the H-bonding properties of these compounds. The influence of methyl-, thio- and halogeno-substitution is discussed for 11 different uracils. © 1990.