»Lo spettro di vibrazione dell'N-ossido di piridina e il problema della vibrazione di valenza NO

Mirone, Paolo

Atti della Accademia nazionale dei Lincei. Rendiconti della Classe di scienze fisiche, matematiche e naturali, Série 8, Tome 35 (1963) no. 6, pp. 530-537

Résumé

The infrared spectra of solid, liquid and gaseous pyridine-N-oxide are reported, together with the Raman spectrum of the liquid. A complete vibrational assignment is proposed, based on gas-phase band contours, depolarization ratios of Raman lines, and comparison with the spectra of pyridine and monosubstituted benzenes. The vibration spectrum of pyridine-N-oxide shows a striking similarity with those of the isoelectronic and nearly isobaric molecules fluorobenzene and phenol. There is no true NO stretching frequency: three A1 vibrations, at 1252, 837 and 544 cm—1, all involve considerable NO stretching. Similarly two B2 vibrations, at 512 and 226 cm—1, both involve some NO out-of-plane bending. The NO in-plane bending mode falls at 468 cm-1. The NO bond of pyridine-N-oxide has essentially the same character as the CO bond of phenol.