VUV spectra of the xenon fluorides

The absorption spectra of gaseous XeF₂, XeF₄, and XeF₆ have been accurately measured in the photon energy range from 6 to 35 eV with the use of the synchrotron radiation of DESY. The vibrational structure of several Rydberg transitions could be resolved. The spectra are interpreted and most of the structures could be assigned. From these data, information about the ionized species is obtained. The assignment of the first two IP's of XeF₄ is corrected.     

13C NMR spectra of acetylated hederagenin glycosides

The¹³C NMR spectra of acetylated derivatives of the following hederagenin glycosides have been studied hederagenin 3-0--L-arabinopyranoside, hederagenin 3-0-[0--L-rhamnopyanosyl-(12)--L-arabinopyranoside], hederagenin 3-0-[0--D-glucopyranosyl-(12)--L-arabinopyranoside], hederagenin 28-0--D-glucopyranoside, and hederagenin 28-0-[0--L-rhamnopyranosyl-(14)-0--D-glucopyranosyl-(16)--D-glucopyranoside]. The spectra give information about the monosaccharide composition, the position of attachment of the carbohydrate chain, and the configurations of the glycosidic bonds, and, in some cases, the orders of the bonds.Pacific Ocean Institute of Bioorganic Chemistry of the Far Eastern Scientific Center, Academy of Sciences of the USSR, Vladivostok. Translated from Khimiya Prirodnykh Soedinenii, No. 3, pp. 359–362, May–June, 1980.     

Fluorine absorption spectra and some fluorides in condensed state

The absorption spectra of liquid F₂, NF₃, N₂F₄, CF₄, BF₃, NF₃, SF₆ have been obtained at diminished temperatures in the near ultra-violet region of the spectrum. It is shown that the absorption spectrum does not differ from the spectra in the gaseous phase, therefore the elementary absorption act is characterized by the cross section of photon absorption by an individual molecule. The absorption cross sections of the above mentioned molecules are represented in the liquid phase, which do not differ strongly from absorption cross sections of these molecules in the gaseous phase. The dependence of the absorption cross sections of liquid fluorine on its concentrations in solutions with N₂, Ar, NF₃, O₂ at - 196°C has been studied. The cross sections of photon absorption by the fluoride molecule in different liquid media with small fluorine concentrations have been obtained.     

Infrared spectra and polymorphism of thiobenzanilide

The infrared spectra of thiobenzanilide, C₅H₅C(=S)NHC₆H₅, and it's deuterated analogue have been recorded between 4000 and 300 cm^?1, at room and liquid nitrogen temperature. Depending on crystallization conditions, thiobenzanilide can give, at least four different spectra, which belong to four polymorphic modifications.     

Infrared spectra of organosilanes and polysilanes

Conclusions The frequencies of the valence vibrations of the Si-H bonds in organosilanes are subject to the influence of hyperconjugation. In polysilanes and in compounds with a Si-Ge or Si-Sn link the effects of hyperconjugation are even greater.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 5, pp. 1194–1196, May, 1970.     

Infrared spectra of diphenylphthalide and polydiphenylenephthalide

The splitting of the ν(C=O) absorption band (AB) of about 12 cm⁻¹ is found in the IR spectra of diphenylphthalide (DPP) in the crystalline phase and CCl₄ solution. In the crystalline phase, this splitting is likely to be caused by the inequivalence of DPP molecules in the crystallographic cell, while in the solution, by the dimerization of DPP molecules via dipole-dipole and/or hydrogen bonds. A theoretical low-frequency shift of the ν(C=O) AB for a complex of two DPP molecules (in comparison with a single molecule) is 14 cm⁻¹ in the PBE/3ξ approximation, which is close to the experimentally observed splitting. In two quantum chemical approximations (B3LYP/6-311G(d,p) (I) and PBE/3ξ (II)) the optimal structure and vibrational spectrum of DPP are calculated. Approximation I better reproduces the intensities, whereas approximation II better reproduces the IR frequencies of the DPP spectrum. Almost all 48 ABs of the IR spectrum of DPP are assigned to theoretical normal vibrations (modes). Based on the potential energy distribution over natural coordinates and the visualization of vibrations, experimental ABs (and the corresponding modes) are assigned to the stretching and bending vibrations of certain bonds in the DPP molecule. In particular, ABs at 1107 cm⁻¹ and 970 cm⁻¹ are assigned to the ν(-OC-O-) and ν(-C-O-) stretching vibrations, respectively, of the DPP lactonic ring, which differs from the previously accepted assignment. The results of the interpretation of the DPP spectrum are used to assign a number of ABs in the IR spectrum of polydiphenylenephthalide (PDP), for which DPP is a model compound. According to the calculations in approximation II of the vibrational spectrum of a model valence-bonded dimeric molecule, the intense complex AB at 800–870 cm⁻¹ in the IR spectrum of PDP is mainly due to the out-of-plane bending vibrations of C-H bonds in the 1,4-substituted benzene rings of polymer biphenyl moieties and the bending vibrations of the lactonic ring.     

Infrared spectra of pyrroles and dipyrrylmethanes

The IR spectra of 18 substituted pyrroles and 6 substituted dipyrrylmethanes are investigated. It is shown that the position of the valence vibrations frequency of the free NH group, _free NH depends on the number of substituents in the ring. The frequency is influenced by the electronegativity of a substituent, the effect of an - being much more marked than that of a -substituent. The stability of the hydrogen bond increases with increase in substituent electronegativity. When two electronegative substituents occupy the and positions, they have a mutually weakening effect. The _C=O (acetyl) absorption bands in pyrrolecontaining compounds are situated 40–60 cm^–1 lower than in aromatic ketones and greatly depend on the position and nature of the substituent in the pyrrole ring.     

Infrared spectra of pentafluoropropionate esters

Infrared spectra obtained for seven alkyl esters of pentafluoropropionic acid show that six of the nine stretching vibrations of the CF₃CF₂COO group and the three CF₃ deformation vibrations have characteristic frequencies, with average deviations of 5 cm^-1 or less. These frequencies are compared with the corresponding values in the acid and the trifluoroacetate esters.     

Infrared spectra of oxine chelates

The infrared spectra of thirty-three oxine chelates were run in the wave-length range from 2–15 μ. By comparison of both wavelength and intensity of the absorption bands, water of crystallization can be determined, the tungsten, uranium and molybdenum and titanium chelates can be conclusively identified and distinctive characterization of most of the other chelates is also possible.     

Infrared spectra of soluble polytoluidines

IR spectra of soluble poly-o-toluidine (POT) and poly-m-toluidine (PMT) have been studied. Preliminary assignment of their IR spectra is given by comparing their spectra in HCl and I₂, doped states and in subsequently NH₃ dedoped state with that in intrinsic state.