THE VIBRATIONAL SPECTRA OF PYRIDINE, PYRIDINE-4-d, PYRIDINE-2,6-d2, AND PYRIDINE-3,5-d2

The infrared spectra of pyridine and pyridine-4-d in the vapor state and of pyridine-2,6-d2 and pyridine-3,5-d2 in the liquid and vapor states have been obtained. The Raman spectra of pyridine-4-d, pyridine-2,6-d2, and pyridine-3,5-d2 as liquids have also been obtained together with depolarization ratios. The vapor band contours for pyridine support the assignment of Corrsin, Fax, and Lord in most part in preference to the assignment of McCullough and co-workers but it was found necessary to reassign the b2 frequencies to give agreement between calculated and observed thermodynamic functions. The infrared and Raman data on pyridine-4-d are in agreement with the reported assignment for the a1, a2, and b1 modes but it was found necessary to reassign the b2 frequencies consistent with the present assignment in pyridine. A complete vibrational assignment for pyridine-2,6-d2 and pyridine-3,5-d2 has been made consistent with the present assignment in pyridine.