Scaled Quantum-Mechanical Force Field and Vibrational Spectra of 3-Methylthiophene

The infrared and Raman spectra of 3-methylthiophene at room temperature have been recorded and measured. A general assignment of its vibrational fundamentals has been proposed on the basis of these experimental data. An ab initio quadratic force field calculation at the 6-31G** level was carried out. The optimized molecular structure, frequencies, potential energy distribution, infrared intensities, and Raman activities obtained were in a good agreement with the experimental results.