Valency oscillation

Hofrnaim first formulated the concept of mixed oxidation states for Prussian blue and other iron-containing mixed valence species. The electronic origin of the color, of course, remained obscure until the development of quantum mechanics. Another concept, described as valence oscillation , was used by Hofinaim and Hoschele following the realization that organic dyes were often found to be unsaturated species with valence resonance an example is cerium-uranium blue (3). 

The oscillations of a polyatomic molecule may be divided into two types. First, the valency oscillation in which the atoms move in the direction of the line joining the two nuclei and in which only the internuclear distance changes during the course of the vibration. Secondly, the deformation oscillation in which the valency angle changes. Clearly diatomic molecules can only show vibrations of the valency type. 

In the IR spectra of copolymers in the region 1000-1100 cm, the characteristic asymmetric valence oscillations of the sSi-0-Si= bonds are found, beside the absorption bands at 1020 cm, where the absorption bands of the linear siloxane overlap the absorption bands of sSi-0-Si= bonds in cyclotrisiloxane ring. From the literature it s known that the absorption bands at 1075-1080 cm are characteristic for =Si-0-Si= bonds in cyclotetra-and - pentasiloxane rings. The transition from dimethylsiloxane links with n = 2ton 51 increases the signals of asymmetric valence oscillation for =Si-Me bonds, as compared with =Si-Ph at 1410 -1412 and 1435 cm. ... 

Table 6.11 shows the results of elementary analysis, physical chemical properties and the yield of ethylsiloxane oligomers containing cyclic fragments in the side chain. In the IR spectra of oligomers with cyclic fragments in the side chain one can observe the absorption bands characteristic of asymmetric valence oscillations of the =Si-0-Sis bonds in the region 1020 and 1080 cm characteristic of both linear siloxane links and cyclosiloxane rings. In the IR spectra one can also observe absorption bands for unreacted =Si-H bonds at 2160 cm. ... 

Osdiiatlons of the methanol moleeulB a valence ssdilation of the OH-group b valence oscillation of the CH3-groLp... 

O. icillations of the PVAc mokiculc A valence osdilalien of the C=0-group, 1. harmonic vibration B r valence oscillation of the CH-.CH2-CH3-grotJp... 

Fig. 8. Valence oscillations and rotations in rubber and gutta percha. (The diameters of the atoms have been designed too small by comparison, for reasons of distinctness) According to Bunn ...

In precise investigation of atomic oscillations in the molecule, it appears that two different types are again distinguishable valence oscillations and deformations or break oscillations. The former consist of the periodic motion of the atoms in the direction of the main valences linking them the oscillation therefore causes an intermittent variable extension and contraction of any bond distance, a few data for which are shown in Table 2. In the break oscillations, however, the deformations of the atom are executed perpendicular to the bond direction and effect a periodic increase and diminution of the valence angle numerical data are also given for these in Table 4. 

In the FTIR spectra one can observe absorption bands at 1020 cm characteristic for asymmetric valence oscillation of linear =Si-0-Si= bonds, also there are new absorption bands at 820-840, 917 cm characteristic for epoxy rings. Absorption band at 1150 cm corresponds to asymmetric valence oscillation for the C-O-C simple ether bonds. In the H NMR spectra of compounds I and II one can observe singlet signals for methyl protons attached at silicon atom with chemical shift 6=0.1 ppm, multiplet signals for protons of methylene and methine groups in oxirane ring with center of chemical shifts 6=2.7- 2.4 ppm and 6=2.5 ppm accordingly. 

The FTIR spectra of oligomers revealed that the absorption bands characteristic for =Si-H bonds in the range 2160-2170 cm do not vanish completely. In the FTIR spectra one can see the absorption band at 850, 920, and 4545-4550 cm characteristic for epoxy groups, the absorption bands at 1020-1100 and 1150 cm corresponds to asymmetric valence oscillation for the linear =Si-0-Si= and C-O-C simple ether bonds, as well as absorption bands in the range 2900-2950 cm, typical for valence oscillations of the CH bonds in the CH groups in the ethylene bridges and absorption bands at 1270 cm characteristic for =Si-Me bonds. 

According to the investigations with transmission electron microscopy the formation of carbon nanofilm structures consisting of carbon threads is characteristic for copper/carbon nanocomposite. In contrast, carbon fiber structures, including nanotubes, are formed in nickel/carbon nanocomposite. There are several absorption bands in the range 2800-3050 cm which are attributed to valence oscillations of C-H bonds in aromatic and aliphatic compounds. These absorption bonds are connected with the presence of vaselene oil in the sample. It is difficult to find the presence of metal in the composite as the metal is stabilized in carbon nanostmcture. At the same time, it should be pointed out that apparently nanocomposites influence the structure of vaselene oil in different ways. The intensities and number of bands for Cu/C and Ni/C nanocomposites are different for ... 

Oscilations of the PVAc molecule A valence oscIMatlon of the C=0-graup. 1. harmonic vlbratint B valence oscillation of Ihe CH-,CH2 CHa-group... 

---