Deformation frequencies

Aminopyrroles are usually formulated as such because they are quite strong bases and do not easily lose ammonia by hydrolysis. In agreement with the amino formulation, the infrared spectrum of the a-aminopyrrole 93 (R = H) contains a v NHg doublet and a band near 1660 cm" corresponding to the NH2 deformation frequency, and the infrared spectrum of the acetamino derivative is in agreement with the structure 93 (R Ac). However, a stable imino compound, probably with structure 94, has been isolated. ... 

The spectra of all metal alkyls studied by Kaesz and Stone (46) show a band at about 2750 cm-1 assignable to an overtone of the symmetric methyl deformation vibration at about 1375 cm-1. If we assign the band at 2812 cm-1 to this overtone, the symmetric methyl deformation frequency would occur at about 1406 cm-1, i.e., near the broad band centered at 1415 cm-1. If we accept this assignment and take account of the fact that... 

Blinc and Iladzi (23a) have shown that this frequency, which lies at about 1650-1820 cm-1 in a series of afe-dioxime complexes, is more probably the in-plane O-H deformation frequency, and that the O-H stretching frequency lies in the range 2340-2380 cm-1 they find the out-of-plane O-H vibration between 860 and 930 cm-1. It seems likely that the hydrogen atoms do not lie directly between oxygen atoms, but it is still uncertain whether they are symmetrically disposed with respect to the oxygen atoms or not. 

The v<2 Region. As discussed earlier, there should be one mode in this intermediate frequency range for a linear or bent M-H-M array. However, in these more complex metal carbonyl complexes, the bent form of (OC)sM-H-M(CO)5 should exhibit two deformation frequencies because the presence of the carbonyl ligands transforms what would have been a rotational motion for... 

The infrared (IR) spectra of 1,10-phenanthroline, its hydrate and perchlorate in the region 600-2000 cm-1 have been obtained, and the principal features of the spectra interpreted.66 Further studies on the IR spectra of 1,10-phenanthroline,67-69 substituted 1,10-phenanthrolines,70,71 and 1,7-phenanthroline67 have also been reported. The IR spectrum of 4,7-phenanthroline in the region 650-900 cm-1 has been analyzed, and the C—H out-of-plane deformation frequencies were compared with those of phenanthrene and benzo[/]quinoline.72 The IR spectra of salts of 1,10-phenanthroline have been taken, and the NH vibrations determined.28,73 Infrared spectroscopy has been used to detect water associated with 1,10-phenanthroline and some of its derivatives on extraction into nitromethane from aqueous solution.74 The Raman spectrum of 1,10-phenanthroline has been compared with its IR spectrum.75 Recently, the Raman and IR spectra of all ten isomeric phenanthrolines were measured in solution and solid states, and the spectra were fully discussed.76... 

Stein, R. S. Interaction of methylene deformation frequencies in paraffin crystals. II. A theoretical treatment of the interaction of vibrations. J. chem. Phys. 23, 734—736 (1955). 

At the most empirical level, IR spectra provide valuable fingerprints of substances since the spectrum is so sensitive to structural details. At a slightly higher level of elaboration, we can identify specific bonds or groupings of atoms whose stretching and deformation frequencies fall... 

Contrary to the weak cage response, the guests properties experience considerable changes. In the encapsulated CH4 molecule, the C-H bonds are 0.014 A shorter than in the free molecule (Table 1). This entails a considerable increase in the C-H stretching frequencies a and t (by 140-150 cm-1) and a small increase in the deformation frequencies e and l (by 10-12 cm-1) (Table 2). For the stretching frequencies, similar shift values (138 cm-1 for symmetrical and 152 cm-1 for antisymmetrical modes) were calculated for the CH4 C60 cluster in Ref. [39] within the MP2 approximation. 

The internal viscosity of the macromolecule is a consequence of the intramolecular relaxation processes occurring on the deformation of the macromolecule at a finite rate. The very introduction of the internal viscosity is possible only insofar as the deformation times are large, compared with the relaxation times of the intramolecular processes. If the deformation frequencies are of the same order of magnitude as the reciprocal of the relaxation time, these relaxation processes must be taken explicitly into account and the internal viscosity force have to be written, instead of (2.26) as... 

Jolly, W. L. The Symmetrical Deformation Frequencies of Methyl, Silyl, and Germyl Groups. J. Amer. chem. Soc. 85, 3083—3085 (1963). 

In a subsequent investigation, with Roos and Kampschreur (1989), Northolt extended the modified series model to include viscoelasticity. For that an additional assumption was made, viz. that the relaxation process is confined solely to shear deformation of adjacent chains. The modified series model maybe applied to well-oriented fibres having a small plastic deformation (or set). In particular it explains the part of the tensile curve beyond the yield stress in which the orientation process of the fibrils takes place. The main factor governing this process is the modulus for shear, gd, between adjacent chains. At high deformation frequencies yd attains its maximum value, ydo at lower frequencies or longer times the viscoelasticity lowers the value of gd, and it becomes a function of time or frequency. Northolt s relations, that directly follow from his theoretical model for well-oriented fibres, are in perfect agreement with the experimental data if acceptable values for the elastic parameters are substituted. 

The infrared spectrum of neat HA1[N(C2H5)2]2 exhibits Al—H stretching and deformation frequencies at 1822 and 692 cm"1, respectively. The compound can be distilled under high vacuum using a short-path distillation apparatus. It decomposes at 240° to give products of unknown composition.6 The compound can be stored indefinitely at room temperature in an oxygen- and water-free environment. 

---