N—O Stretching Vibrations

1 N—O Stretching Vibrations Nitro Compounds In the nitroalkanes, the bands occur near 1550 and 1372 cm-1. Conjugation lowers the frequency of both bands, resulting in absorption near 1550-1500 and 1360-1290 cm-1. Attachment of electronegative groups to the a carbon of a nitro compound causes an increase in the frequency of the asymmetrical N02 band and a reduction in the frequency of the symmetrical band chloropicrin, C13CN02, absorbs at 1610 and 1307 cm-1. 

Because of strong resonance in aromatic systems containing N02 groups and electron-donating groups such as the amino group, ortho or para to one another, the symmetrical N02 vibration is shifted to lower frequencies and increases in intensity. p-Nitroaniline absorbs at 1475 and 131( cm 1. 

Nitrites Nitrites display two strong N=O stretching bands. The band near 1680-1650 cm1 is attributed to the trans isomer the cis isomer absorbs in the 1625-1610-cm1 region. The N—O stretching band appears in the region between 850 and 750 cm-1. The nitrite absorption bands are among the strongest observed in IR spectra. 

Nitroso Compounds Primary and secondary aliphatic C-nitroso compounds are usually unstable and rearrange to oximes or dimerize. Tertiary and aromatic nitroso compounds are reasonably stable, existing as monomers in the gaseous phase or in dilute solution and as dimers in neat samples. Monomeric, tertiary, aliphatic nitroso compounds show N=0 absorption in the 1585-1539 cm1 region aromatic monomers absorb between 1511 and 1495 cm-1. 

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N O Stretching Vibrations Nitro Compounds In the nitroalkanes, the bands occur near 1550 and 1372 cm-1. Conjugation lowers the frequency of both bands, resulting in absorp-... 

Furthermore, there exist three species of adsorbed NO molecules on Pt(l 1 1) saturated at low temperature. However, only one peak with a N-O stretching vibration corresponding to NO adsorbed on the on-top site can be observed in RAIRS [35]. Recent results of structure analysis obtained by structure-sensitive methods and by a theoretical study have solved the problems in the interpretation of experimental results of laser-induced NO desorption from Pt(l 11). 

Recently, Matsumoto et al. have analyzed the adsorption structure of NO on Pt(l 1 1) by STM and HREELS on the surface saturated with NO at 70 K and then annealed to 215 K [39], and further by LEED and RAIRS on the three different 2x2 surfaces at low temperatures (90-150 K) [40]. Only molecular NO is desorbed thermally from the Pt(l 1 1) surface with NO saturated at 70 K and three desorption peaks a, (3 and 7 are observed in the thermal desorption spectrum (TDS), as shown in Fig. 7. At low coverages only the a peak in TDS appears at 350 K a new (3 desorption peak at 310 K and a third peak of 7 species at 185 K appear with increasing coverage. However, only one peak of the N-O stretching vibration can be observed in RAIRS [35]. After annealing the NO-saturated surface to 225 K,... 

Desorption from fee hollow species Figure 13a shows RAIRS spectra of NO adsorbed on the Pt(l 1 1) surface after NO exposure of 0.3 L, where only the fee hollow species exists (Fig. 9a), and only one peak for the N-O stretching vibration can be observed at 1490 cm-1 [57]. After laser irradiation at X = 193 nm for 10 and 20 min at 80 K with a laser fluence of 3-5 mJ/cm2, this peak intensity decreases,... 

N]-piperidine-nitroxide radicals, Morat and Rassat have confirmed that the absorption at 1373 7 cm i is due to the N—O stretching vibration. It has been shown that 2,2,6,6-tetramethylpiperidine nitroxide radicals (359) efficiently quench singlet oxygen, whereas the parent piperidines exhibit only low activity. ... 

The structure of nitrous oxide is given below. Place the individual bond dipole moments on the diagram. Would the N O stretching vibration absorb infrared radiation ... 

Table J4.2 Organic nitroso compound N O stretching vibrations...

Table 22.22 Nitrosyl complexes N-O stretching vibration bands...

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