Stretching frequencies, ethylenic

Equipment, electrorefining process. 419/ ER—See Electrorefining Ethylenic stretching frequencies of... 

Carbonyl and ethylenic stretching frequencies of a series of 3-oxo-steroids show solvent effects due to solute-solvent association, which appears to include C=C tt-H bonding. The association of 5a-cholestan-3o - and -3j8-ols in solution has also been studied by i.r. spectroscopy these compounds form both dimers and tetramers. 

Pyridine 1-oxide, like pyridine, can act as a ligand in transition metal complexes, but unfortunately good stability constants are not known. However, Shupack and Orchin have found that the C===C stretching frequency of the ethylene ligand in trans-ethylene pyridine 1-oxide dichloroplatinum(II) varies linearly with the pA and hence with the C7-value (ct+ or a, respectively) of substituents in the pyridine oxide. The data for the above reaction series are included in Table V. 

Dipole moments of substituted nitriles were correlated with the a constants by Taft and with the Op constants by Charton (18). In addition to dipole moment data, some information is available on the C=N stretching frequencies of substituted nitriles. The sets studied are reported in Table XXXVI. Results of the correlations with eq. (2) are given in Table XXXVII, and values of Pr are set forth in Table XXXVIII. The correlation of the dipole moments of substituted nitriles with eq. (2) gave significant results, which were very much improved by the exclusion of the value for X=I (set 36-1-2). In contrast to the results obtained for substituted ethylenes, acetylenes, and benzenes, the value of /3 obtained for dipole moments of substituted nitriles is not significant. The value of a obtained for the substituted nitriles is comparable to the value of a observed for the substituted acetylenes. 

Anti-Stokes picosecond TR spectra were also obtained with pump-probe time delays over the 0 to 10 ps range and selected spectra are shown in Figure 3.33. The anti-Stokes Raman spectrum at Ops indicates that hot, unrelaxed, species are produced. The approximately 1521 cm ethylenic stretch Raman band vibrational frequency also suggests that most of the Ops anti-Stokes TR spectrum is mostly due to the J intermediate. The 1521 cm Raman band s intensity and its bandwidth decrease with a decay time of about 2.5 ps, and this can be attributed the vibrational cooling and conformational relaxation of the chromophore as the J intermediate relaxes to produce the K intermediate.This very fast relaxation of the initially hot J intermediate is believed to be due to strong coupling between the chromophore the protein bath that can enable better energy transfer compared to typical solute-solvent interactions. ... 

Carbonyl, stretching frequency, 30 191 Carbonylation, 28 80, 31 39-46 ethanol, 31 45-46 ethylene, 31 46 higher alcohols, 31 45-46 methanol, 31 39-45 of primary linear alcohols, 34 90-94 activation parameters for, 34 91 benzyl alcohol, 34 90 ethanol, 34 90 1-propanol, 34 90 mechanism for, 34 93 variation of products with pressure, 34 92... 

Eischens and Pliskin have interpreted the infrared spectra of ethylene chemisorbed on nickel dispersed on silica 32). When introduced to a surface previously exposed to hydrogen, ethylene gave rise to absorption bands which correspond to the C—H stretching frequencies of a saturated hydrocarbon (3.4-3.5 p) and a deformation associated with a methylene group (6.9 p). A weak band at 3.3 p was attributed to an ole-finic C—H. Treatment of the chemisorbed ethylene with hydrogen caused the spectrum to change to one which was interpreted as due to an adsorbed ethyl radical. Apparently in the presence of hydrogen most of... 

Bellamy [27] examined a number of nitric esters, among them ethylene glycol dinitrate and pentaerythritol tetranitrate and found the stretching frequencies to be 1650-1610 and 1300-1250 cm-1 respectively. 

For the detection of subtle differences within a given series of closely related compounds, spectroscopic studies are generally more useful than diffraction studies. An inverse correlation between the C=C bond lengths and the infrared stretching frequencies, vc-c, in a series of ethylene complexes has been observed (63) (Fig. 5A). There is at present some discussion about the nature of the infrared band observed around 1500 cm-1 [(70) and referen3es therein]. It is found that the normal mode contains... 

This relationship between K and -interaction is supported by the electronic and ESCA spectra of these complexes (41). A rough correlation has also been shown to exist between the A8 values for a series of ethylene complexes and both the C=C stretching frequency and the C=C bond length (41, 42). In addition, several groups have shown that the upheld shift of the olefinic carbon atoms in phosphine complexes correlates with the basicity of the phosphine (vide infra). 

Figure 7. Correlation between the ethylenic (C=C) stretching frequency and the main absorption maximum of the retinyl moiety in a variety of pigments and in free retinal Schiff bases in solution. (Data, based on resonance-Raman experiments at room temperature, from refs. 221, 225, 226, and 323.)...

The v(C-Pt) stretching frequency is higher for adsorption on the di-a mode than on the n mode, indicating a stronger bond in the former case. The calculated vibrational frequencies for the di-a adsorption mode agree fairly well with the available experimental data [62] but the calculated values for the n-top adsorption mode differ significantly from the experimental data [62], This strengthens the idea that, on a Pt(lOO) surface, at low temperatures, the ethylene molecule adsorbs only as a di-a complex. 

In Table VII are recorded mean values for in a number of ethylene-metal carbonyl complexes and parent metal carbonyls as well as values for the double-bond infrared stretching frequency rc c the magnetic shielding parameter t for ethylene in those transition metal complexes for which data are available. Although with the metal carbonyl complexes, differences of geometry, oxidation state, etc., do not permit a correlation to be drawn between the absolute values of rco and for the various complexes, it is quite apparent from the tabulated data for the Mo, Mn, and Fe complexes that for a given metal. 

Use SpartanView to display the vibrations of ethane, ethylene and acetylene, and identify the carbon-carbon stretching frequencies in each. (Note that calculated frequencies are about 10% larger than observed frequencies.) How does frequency vary with bond strength ... 

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