Infrared, raman, and 13C NMR spectra of two crystalline forms of (1R,3S)-3-(p-thioanisoyl)-1,2,2-trimethylcyclopentanecarboxylic acid.

A comparative structural analysis of the two polymorphic forms of (1R,3S)-3-(p-thioanisoyl)-1,2,2-trimethylcyclopentanecarboxylic acid has been performed with infrared, Raman, and 13C NMR spectroscopy. The results are compared with those of the crystallographic and thermal studies on the two forms published in previous papers. The enantiotropism of the polymorphs as well as the differences in the conformation of the carboxyl group and the resulting intermolecular hydrogen bonds were confirmed by the infrared and Raman studies.