Discussion des modes normaux des groupements amides cis et trans à partir des champs de force du σ-valérolactame et du N methylacetamide

Champ de force de valence et modes normaux de vibration de la glycylglycine et du monochlorhydrate monohydrate de glycylglycine

“…On sait que ces modes lnettent en jeu les coordonnees v(CN) peptidiques et 6(NH) (17) qui sont trks sensibles a la force des liaisons intermolCculaires; leur frequence peut aussi varier avec I'angle 4,. Nous lie pouvons pas, B ce stade de notre Ctude, siparer l'effet respectif de ces deux parainktres sur la position de ces vibrations.…”

Microwave Spectrum and Molecular Conformation of δ-Valerolactam

“…The normal modes of characteristic vibrations of this compound were analyzed (2) by using the valence force field and referring to the crystal structure of ␣-chloro-␦-valerolactam (6). Carmona measured low-frequency Raman spectrum from 20 to 200 cm Ϫ1 of ␦-valerolactam in CCl 4 solution at different temperatures and deduced from the spectral features that the dimers with C 2 symmetry were predominant (3).…”

“…2), 160 cm Ϫ1 (asymmetric torsion, 2 ), and 101 cm Ϫ1 (ring puckering coupled with other two torsions). The measurement of the IR spectrum reported by Rey-Lafon et al (2) showed that the two absorption lines of 322 and 188 cm Ϫ1 were observed in the range below 400 cm Ϫ1 . The calculated frequencies of 331 and 160 cm Ϫ1 matched with the experimental values (2) of 322 and 188 cm Ϫ1 , respectively.…”

Vibrational spectra and structure of N-methylacetamide in some solid complexes with neutral salts

“…Due to tunnel effect, the mean structure of NMA has the C,y symmetry and the denomination for the normal modes proposed by Miyazawa (8) can be kept. Three spectral regions are selected where the most localized modes appear (8)(9)(10)(11)(12)(13)(14)(15): 400-800 cm-' ( Y~~(~~) ) , 1500-1700 cm-' (amide I and 11) and 3050-3600 cm-' (vNH). The spectra of pure NMA at room and liquid nitrogen temperature are given in Fig.…”