Vibrational studies of N-trifluoroacetyl-phosphoramidic acid dichloride [CF3C(O)NHP(O)Cl2] and N-trichloroacetyl-phosphoramidic acid dichloride [CCl3C(O)NHP(O)Cl2]

A novel 3-acetoxy-2-methyl-N-(4-methoxyphenyl)benzamide: Molecular structural describe, antioxidant activity with use X-ray diffractions and DFT calculations

“…In amide compounds, the N-H stretching vibrations occur in the region 3500 cm -1 [48]. [48,49]. In the present case, the stretching mode of C16=O4 is assigned at the very strong band 1764 cm -1 in the IR spectrum and the B3LYP/6-31G+(d,p) calculations give this mode at 1760 cm -1 .…”

Vibrational spectra of solid cis- and trans-2-thioxohexahydroquinazolin-4(1H)-one and theoretical calculations towards the interpretation of its thermal reactivity

“…These new peaks are observed with their spectral intensities as a combination of the corresponding fundamentals. 21 In several cases, 19,20,[22][23][24] this effect is enough to explain the experimental/calculated spectral differences, but when the molecule shares both N-H and C-H groups, the bands attributed to the Fermi effect appear in the 3650-3300 cm À1 region while in the Raman spectra, they are observable as broad low intensity signals (centered at 3161 and 3184 cm À1 , for cis and trans NH tautomers, respectively). 25,26…”

“…It is reported that the calculated wavenumber (DFT method) of the N-H stretching vibration in molecules where the bond is participating in H-bridges, falls AE200 cm À1 from the pure N-H experimentally observed. [17][18][19][20] For both cis and trans NH tautomers, the calculus predicts for the Raman spectra: 3245 cm À1 (block B) and 3220 cm À1 (A block) (attributed to the signals located at 3165 cm À1 ), for the cis NH; and 3257 cm À1 (B block) and 3235 cm À1 (A block), assigned to the band at 3178 cm À1 for trans NH.…”

“…The most stabilizing interaction in molecules containing the N-C]O moiety is the delocalization from the lone pair of the nitrogen atom toward the pi antibonding orbital of the carbonyl group (LP N / p*C]O) that contributes largely to the resonance effect, 19,20,[31][32][33][34] and it was also observed in hexahydroquinazolines. From the point of view of the delocalization, it is reasonable to think that this moiety will remain bonded aer the thermic rupture independently of the tautomer considered.…”

Different orientations of C=O versus P=O in P(O)NHC(O) skeleton: the first study on an aliphatic diazaphosphorinane with a gauche orientation

“…This is attributed to the presence of relatively strong HB between [59], the experimental frequency is 3064 cm -1 and the theoretical through two different methods are 3291 and 3251 cm -1 . It is well-known that the HB causes dramatic changes in the structural parameters of the molecules as observed in the infrared spectra [60,61]. So, the lower N C(O)NHP(O) -H and P=O frequencies in 2 relative to those similar in 1 (NH: 3091 and 3199 cm -1 and P=O: 1228 and 1281 cm -1 ) are attributed to a stronger HB.…”