Fundamental vibrations of furan and deuterated derivatives

Infrared study of the C—H stretching region of five-membered heterocyclic compounds

“…The gas spectrum recorded by us shows a clear R-Q-P envelope with the Q peak centred at 3162 cm-l. We prefer, therefore, to change Rico's assignment and take this band as vC-, of the Al species. In agreement with this assignment, the corresponding strong Raman line at 3 154 cm-I is polarised (9 3132 cm-l, where the Q branch of another band having R-Q-P structure is found. The two B2 modes are assigned to the bands at 3139 and 3123 cm-l which lack Q peaks.…”

“…For the C-H stretching of furan, we start with a discussion of the assignment proposed by Rico et al (8,9). These authors give values of 3167 (calculated by the complete isotopic rule) and 3140 cm-I for the Al C-H motions and values of 3161 and 3129 cm-I for the B2 ones.…”

“…Although the vibrational spectra of pyrrole (1-7), furan (6)(7)(8)(9)(10)(11)24), thiophene (6,10,(12)(13)(14)(15)(16)(17)(18), and selenophene (19)(20)(21)(22)(23) have been extensively investigated, considerable discrepancies in the assignment of the 3200-3000 cm-I region exist. This is due to a number of factors: (i) four fundamentals (two Al and two B2) must be assigned, but only two sharp peaks are usually observed both in the infrared and in the Raman spectra; (ii) the band profiles of the gas spectra are not well defined, especially in the case of pyrrole and furan; (iii) the Raman polarisation data are scanty and seem to be reliable only for thiophene (14) and selenophene (21).…”

High Resolution IR-Spectra of Furane and Thiophene

“…Microwave data and low-resolution IR data of both molecules have been published [1][2][3][4][5][6][7][8][9][10][11][12][13][14]. Those earlier papers reported the rotational and centrifugal constants of the ground state, the molecular structure, and gave a vibrational analysis of band origins and the force field.…”

“…The high-resolution Fourier transform spectrometer at Giessen and the Cologne diode-laser spectrometer were utilized for this purpose. In the previous papers [1,2] the v 13 out-of-plane fundamental bands of both molecules are labeled as v 19 ; here we follow Mulliken's recommendation for notation [15]. The out-of-plane vibrations belong to A 2 and B x symmetry species of C 2v , and the modes are numbered according to descending order of frequency in each symmetry block.…”