CONFORMATIONS AND VIBRATIONS OF DICARBOXYLIC-ACIDS - AN AB-INITIO STUDY

The conformations of the higher dicarboxylic acids HOOC(CH2)(n)COOH, n = 1-4, the hydroxymalonic acid have been studied at the HF/4-21G leve l of theory. The conformational characteristics of these acids have be en elucidated through potential energy scans at this level. The vibrat ional frequencies of all the dicarboxylic acids have also been evaluat ed at this level. Calculations at the HF/6-31G* level of theory were also carried out on malonic, hydroxymalonic and succinic acids. They h ave been assigned to the solid state Raman and IR spectra of the dicar boxylic acids. The potential energy distributions, Raman activities an d IR intensities calculated at the levels indicated have been used as aids in making the assignments. The calculated frequencies have also b een compared with the frequencies evaluated at the MP2/4-31G level fo r oxalic acid.