Spectrum, infrared, definition

In 1939, the ultraviolet spectrum of 4-methylquinol-2-thione was reported to differ from that of the 2-alkylthio analog, and the former compound was concluded to exist in the thione form. However, other investigators were unable to reach any conclusions from ultraviolet and infrared spectral data concerning the tautomerism of quinol-2- and -4-thione. A definitive pK and ultraviolet spectral investigation by Albert and Barlin has recently established that the thione forms of quinol-2- and -4-thione and of isoquinol-1- and -3-thione (cf. 202) greatly predominate (Table V). The infrared... 

The eigenvalues calculated either by the Merrifield or ABO method are nearly identical. As can be seen, this analysis leads to the prediction of a number of low-lying infrared absorption bands for this complex. In a discussion of the structure of the Creutz-Taube ion, I pointed out some time ago (27) that the evidence definitely favors a well-delocalized ground state (6 < 1), and predicted that these infrared bands would, thus, not be observed. In a recent publication, Krausz, et al., report that a search for the bands indeed gave negative results, and withdraw their proposed interpretation of the spectrum (48). 

To conclude, it seems that the nature of the anharmonic coupling between a high frequency intramolecular mode and a thermally excited low frequency mode is understood. It turns out that the strength of the influence on the infrared spectrum critically depends on the values of (Oq, Sm and t. However, we have to wait for more experimental data on these low frequency modes, probably obtained with the helium atom scattering technique, bdbre we can make more definite conclusions. 

There are definite distinct lines in the atomic emission spectrum of hydrogen. These lines are seen in the visible part of the spectrum and there is also a series of lines in the infrared and another series in the ultraviolet part of the electromagnetic spectrum. So, although hydrogen is the simplest element with only one electron per atom, its atomic emission spectrum is fairly complicated. 

Reaction of metallic europium with cyclopentadiene in liquid ammonia yields [478] a yellow europous-dicyclopentadienyl (eq. 41) complex. Magnetic measurements on this compound (jn = 7.62 Bohr magneton) and its infrared spectrum definitely confirm the divalent state of europium. 

In arriving at a satisfactory analysis of the spectrum we must make use not only of the polarization data, but also of the results of deuteration studies, full [Narita, Ichinohe, and Enomoto (145)] and partial [Folt, Shipman, and Berens (55)], and studies of C—Cl frequencies in small molecules. [Mizushima, Shimanouchi, Nakamura, Hayashi, and Tsuchiya (139) Shimanouchi, Tsuchiya, and Mizushima (196)]. The lack of the Raman spectrum is a definite handicap, but is in part mitigated by the expectation that many of the Raman active fundamentals should be close to the frequencies of infrared active fundamentals. 

Primary amines may be readily distinguished from secondary and tertiary analogues by the presence of two absorption bands in the infrared spectrum between 3320 and 3500 cm-1 (symmetric and antisymmetric NH str.). Secondary amines exhibit a single absorption band at about 3350 cm-1 (NH str.). In both cases deformation modes for the NH bond appear at about 1600 cm-1. There is no satisfactory absorption to allow a definitive characterisation in the case of tertiary amines. In the nuclear magnetic resonance spectrum of primary and secondary amines, the nitrogen-bound hydrogens are recognisable by their replaceability on the addition of deuterium oxide. 

The structures of these adducts have yet to be established in a definitive manner. However, the infrared spectrum of [H3BRe(CO)5]- is very similar to that of the parent anion in the CO stretching region,... 

The microwave acoustic effect may be defined as the auditory perception of microwave radiation which is a form of electromagnetic energy which occupies the part of spectrum between ordinary radio waves and infrared and optical waves. This definition may... 

Molecular Models. After selecting the most important fundamental frequencies from which the infrared spectrum is built, it becomes of interest to attribute to each a definite bond or type of vibration. Although such relations are quite speculative, there is now sufficient evidence to establish some of them with a fair degree of confidence. 

L. C16H29NO. Cochromatographs with another alkaloid, and because of this a definitive mass spectrum could not be obtained. Occurs mainly as the 0-acetate (73). 251L O-acetate. C18H31NO2, —,—, ion trap, m/z 293(<1), 250(18), 222(32), 176(77), 148(40), 134(22), 84(80). Infrared data (73). The infrared spectrum is typical for homopumiliotoxins, as is the m/z 84 fragment. 

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