Raman and infrared spectra, ab initio and DFT calculations, and vibrational assignments for 2,3-cyclopentenopyridine

The structural properties of 2,3-cyclopentenopyridine (pyrindan) have been investigated using several spectroscopic and computational techniques. The Raman and infrared spectra of the molecule have been recorded and a full vibrational assignment was proposed on the basis of experimental and theoretical results. The vapor-phase Raman spectrum was successfully obtained at 260°C without sample decomposition. Density functional theory (DFT) and Møller-Plesset (MP2) calculations predict that the presence of the nitrogen atom in the six-membered ring has almost no effect on the barrier to inversion (587 cm−1) and puckering frequency (139 cm−1) as compared to the values previously determined (488 cm−1 and 143 cm−1) for the indan molecule.